Backpack Lake
I have a great suggestion for you. I did this trip in 2007.
Just south of Walden, a good paved/dirt road goes off to the west then dead ends at a trail head just outside the Zirkels Wilderness. Take the only trail from the parking area and walk about 2.5 miles to upper Rainbow Lake. Stay a couple of nights at Rainbow. There is no fee for camping but you must camp in designated sites.
Forget about middle and lower Rainbow Lakes and concentrate on upper Rainbow. Camp on the north side. You will find places to log hop across the outlet.
If you can pull yourself away from upper Rainbow, after catching 12" to 16" cutthroats, rainbows and cuttbows on just about every other cast all day, leave your camp where it is and head over the mountain at the north side of the lake to Ceanathuse (don't know how it's pronounced) Lake. It's an easy walk up the wooded mountain to it's summit because Rainbow is at a higher altitude than Ceahathuse. The walk down the other side is also easy but farther down than you climbed up. Ceanathuse is a long narrow lake with a rating similar to Rainbow. I wouldn't pass up Ceanathuse. After fishing Ceanathuse, walk around the lower end of the mountain you walked up earlier to Rainbow. This is an easy walk.
If you have the time, load your gear, cross back over the outlet and head for the upper end of Rainbow on a well used trail. While walking this trail, you will be a few yards above Rainbow and you will see nice fish everywhere. At the upper end of Rainbow, check the small feeder creek. It's shallow, gin clear water with lots of these Rainbow Lake fish and it's tough to fish.
Stay on the easy to see trail for about one mile until you see a section to the right where there is a lot of smooth large rocky sections, head to the north up this area to Lower Slide Lake. Lower Slide has 8" to 11" cutthroats.
If you want to pass up Lower Slide, which I recommend, continue up the trail to Upper Slide Lake. I suggest not wasting time at Upper because it is loaded with tiny brook trout and no other trout.
Stay on the trail for several more miles until you come to a steep-ish valley which, I believe, runs north and south. When you break out at the top of the valley, you should be able to look down, about one mile, to Roxy Ann Lake. Plan to spend a couple of nights at Roxy. You will not regret it.
I think this trip is +/- seven or eight miles, one way. The trail to Roxy from Rainbow is one you cannot miss.
There may be a bonus waiting for you at Roxy. Over the past 30 or so years, DOW/CPW has experimented, on two occasions, with stocking California golden trout in select high mountain lakes. They abandoned the projects for whatever reasons they had. Roxy Ann was one of the stocked lakes. If you read, in a later edition of the Tim Kelly Guide (been out of print for many years), you will find the description of Roxy Ann as maybe catching a hold over golden. When I was there, I did not catch a golden but I do believe I caught a golden cutthroat hybrid. One 10" cutthroat I caught had a very bright yellow underside. I think this was a hybrid.
On this trip, the two main lakes to concentrate on are Roxy and Rainbow with Ceanathuse also a good choice. If you go, only use a backpack stove. There are so many dead beetle kill evergreens, it's a place just waiting for a fire. If I ever go back, I will spend all my time at Rainbow.
