RMNP is a great location! I would guess that the JMT is similar to RMNP, so you're pretty well dialed in. Just a few thoughts:
I'd definitely recommend a headnet or similar. Bugs aren't as bad as other parts of the country, but can definitely be out at various times based on hatches.
I don't think you'll need the wind pants in August. It's a warm time of the year up there – I've never felt cold enough for those personally.
+1 to another suggestion on leaving rain pants out. I hike in Colorado with them all the time and find the storms are typically brief enough/early enough that I dry out with plenty of time before bed.
Another +1 on the stakes. The backcountry campgrounds in the park are great, but the ground is compacted.
Make sure to check fire bans right before you leave. If they're severe enough, you might have to switch to a canister stove instead (some of the more extreme bans include alcohol stoves).
As a note on the bear canister, keep your food in it whenever you're in camp. They require it for the bears (and rangers will check if you run into one at your site). I use it for the critters. Some of the campsites have almost no ground animals (ie chipmunks) but I've been at a few that are as bad as shelters on the AT. I left a bag of trailmix sitting out on top of my canister and turned around for 30 seconds while setting up my shelter. Turned back around and it had 3 holes in it from the chipmunks.
Fishing – not sure if you have time for – or enjoy – fishing, but RMNP has some of the best fly fishing in the state. Fern Lake has several sites (it's on one of the loops off Bear Lake) and has ridiculously great fishing in August. I sat in one spot last August on a boulder along the lake's edge and could see half a dozen fish trolling the shores. Caught one every 10 minutes or so. It's catch and release in many areas, but still a lot of fun.