I too plan on hiking the Solitude Trail this summer (probably in June if the snow pack allows) along with the Absaroka/Beartooth Wilderness and the Wind Rivers. My pack list is very similar to yours with a couple of differences.
I will be packing a down puffy for warmth in evening and for the inevitable snows/sleet/cold rains. Wool liner gloves suit me better than leather which tends to get slimy and non insulating when wet. Wool doesn't catch fire like fleece will also, so is safer around stoves or wood fires (seems like there were open fire restrictions last year in the Big Horns). If there are fire restrictions will one can of fuel be enough?
One might consider a sun hat for that elevation also. The sun can be brutal, especially above timber line. I also carry a bear canister for the occasional black or brown bear. Can you hang your food?
Around here (Black Hills, SD), which is not far from and similar to the Big Horns, I catch trout with a double hook Bass setup and worms for bait. Just out for meat, no sport involved!
Seldom are you over an hour from a good water source, either glacier run off, or alpine lake. I will only be carrying 1 liter of water with a 1 liter backup container if needed. Water is clear in the Big horns. I have not had problems with filters clogging from silt. It's a wilderness area so live stock are not a problem. Many moose though.
Might see you on the trail!