Followed the route in vtelgarsky's excellent trip report- https://www.wta.org/go-hiking/trip-reports/trip_report-2020-08-31-1243252923 for a 3 day/2 night trip. Camped at Dewey Lake and Cougar Lake.

Trail conditions:

• Road to Mesatchee Creek trailhead has a few sizable potholes but drivable with care.
• The Dewey Lake trail and trail down to Mesatchee had a lot of blow downs and involved climbing over/under/around some big trees.
• Bugs are unrelenting on the Dewey Lake Trail and in the Dewey and Cougar Lakes areas. Repellent didn't deter them and they bit through bug netting and long sleeves. 
• Couple of campsites with awesome views of Tahoma (see pics) along the eastern shore of Dewey Lake before the creek.
• Quite a few Campsites along Cougar Lake were closed for restoration. 
• Nobody on the trails except for the little stretch of PCT after Dewey. Could hear people and dogs at both campsites.
• No running water source on the way back from Cougar Lake for about 7.5 miles until the trail crosses Mesatchee Creek.

Wanted to hike near Rainer with the dogs and found some good options in Dewey/Cougar lakes but needed to make a loop where we didn't start in the national park. 

Started out Friday afternoon about 5PM at the Mestachee Creek Trail-head - at the time the parking lot was totally empty and we parked to the side of the road to leave the campsites open. On the way out we took Dewey Lake Way along the American River and hiked a little less than 6 miles in to camp at a  site along the river right before the trail turns up towards the climb to Dewey Lake. We were the only ones on the trail all of Friday - great quiet hike.

Saturday morning we broke camp and hiked up to Dewey Lake which was very beautiful with low hanging clouds still breaking up over it. After the lake hopped on the PCT - which was the most crowded part of our hike - and then turned off at the American Ridge trail then took the split off to Cougar Lakes. Lots of blueberries along this part of the trail - we definitely had blue stained fingers by the end of the day. Found a great site at the lakes (though many are closed for restoration there's still good spots to be found) and though the lake was probably warm enough (by which I mean not totally frigid) to swim in it was really windy so we settled for dipping our feet in to avoid turning into popsicles when we got out.

Sunday we took the American Ridge trail out to the Mestatchee Creek trail which took us all the way back to the Trailhead. Very nice trails - though very dusty right now - but it was nice to have a soft ground underfoot while going down 3200 ft. We didn't see anyone on the trail until about a mile from the trail-head. I would definitely recommend doing the loop in this order (up on Dewey Lake Way and down on Mesatchee Creek Trail) because the way down on Mestachee Creek is a very manageable incline but very very long and might have been a spirit breaker if we had to go up that way.

All in all a beautiful trip with lots of berries, flowers, nice weather, and beautiful views.

If solitude is what you want only saw 2 groups and not till the final day around American Lake. Went up the Mesatchee to American Ridge.  Several sources of water and 2 had camps associated with them.  Once on the ridge water still at first pond but more at 2nd pond. Camped here bugs were not bad although there were noticeable swarms on the pond - bit of breeze on the ridge and the many dragonflies feasting away! Day hiked the ridge about a mile east of Big Basin.  The trail past Big Basin continues to narrow to an elk track and has some sketchy washout areas -big rocks and juniper for handholds.  I turned back around the second bad one.  It would be beyond my comfort level to cross these with a big pack. The views were astounding and saw lots of elk and coyote prints. No water and flowers are about spent but berries ripe. Next moved camp to Cougar Lake. Again only 1 trickle along the way to wet your bandana. There were a few manageable downed trees.  There is water at the junction with the Cougar Lake Trail.  Note this side trail climbs about 200 ft then drops about 800 ft - quite rooty and rocky.  Very blessed to share the lake with only the resident bear and jumping fish.  Lots of secluded campsites along both lakes so please respect the signage and don't camp on the spit. Continued west on American Ridge to loop out to the PCT - tons of flowers in this section with more water and a stately bull elk.   Continued past Dewey Lakes (bugs were horrible around Dewey Lake)nice waterfall just past lake and even bigger about 1.5 miles. Upper American River ford is just a rock hop and one camp available here. This is the only camp between Dewey Lake and the Mesatchee Creek -American River ford. This trail is also littered with past present and future downed trees.  All were passable and only one required removal of pack. Many little creeklet some murky others clear and watch your step lots of frogs in this area between the fords.  The Mesatchee has no true course thru this section but is easily passable.

Just did 3 days out on American ridge. Started from Goose prairie trail instead of our initially planned start at the end of FS1800, almost the other end of Bumping Lake. The FS road is in pretty bad shape and our drop off car was too low to go all the way.

The climb up on Goose prairie trail was fine. Few trees down and across the trail but nothing too hard. When we hit American ridge, we headed south for about 1.5 miles and decided to set camp there rather than hiking down the bowl and to the small lake. We did go get some water at the lake. Mosquitoes were plentiful. We had amazing views of Mount Adams and Rainier that evening. 
next morning we intended to follow the American ridge to the west, towards Rainier. We walked by the small lake and then lost the trail several times until We could not find our way out of the bowl, in a safe way. We turned around, walk back up to the ridge and headed straight north e1st towards Goat peak. Trying to stay on the trail was challenging. The recent fires have swept away the trail, there is still lot of ashes, and all trees are burned. Not a pretty sight but you have to walk through this to get to Goat peak. We ended up sleeping on the ridge for day 2... amazing views of Rainier, Adams and Bumping lake. That day was challenging no water available while hiking the ridge. We are to ration ourselves. Plan accordingly. 
Day 3 we simply hiked down by Goat Creek Trail... well marked and a smooth time. 
The American ridge would have been great if we had been able to follow the trail consistently. We had to re adjust our path as we kept losing the faint traces of the trail. 
Sunset and sunrise views were great. 
We did not cross anyone while on this hike. 

Overnight up to American Ridge on the Goose Prairie Trail (first TH north of Bumping Lake - parked in a campsite area across the road), along the main American Ridge trail to the ridge summit before camping in a meadow below. Trail was tough to follow and disappeared in many places, which led to a fair amount of annoying bushwhacking on very steep slopes. GPS was very helpful - generally would have been able to stay parallel to the ridge without it, but would have lost a lot more time. I'd wondered if it might be possible to scramble the entire ridge, but it didn't look like it would have been due to cliffs. Bugs were very bad, especially near any water. Zero people. The solitude was nice, but the views weren't amazing until the top, and the trail needs some love. Water was not terribly frequent, mostly the outlet streams from swampy late-summer ponds. Don't think there was any water from the summit until the junction with the Mesatchee trail, but I was able to melt some lingering snow. ~15 miles with a lot of climbing.

Day 2 was more pleasant - trail reappears near the Mesatchee junction and is strong thereafter, with frequent water. Beautiful hike by American Lake and then south on a great section of PCT, down to the big Fish Lake - would have been a long hot climb in the other direction. Nice snow patches for cooling purposes, which my dog appreciated, though the trail was essentially clear. Boring but decent section of trail back to Bumping Lake - doesn't appear on all maps, labeled Bumping Lake Trail with a cutoff via a smaller "Fish Lake Trail" that worked well (but required a river ford). Lots of blowdowns here, but fortunately the trail never disappeared. Then a long and dusty road walk back to the car. The dirt forest roads are nice, but once we hit the paved section cars were speeding in and out of the marina and that was less fun. ~25 miles, mostly going down.