I'm not going to say stop now, this is a once in a life time adventure, go for it and enjoy every minute of the trip. When to hit to Rockies, July/Aug/Sept you pick a time. So much water so little time. If you guys are into a little hiking I would recommend the North Platte above Saratoga, WY it will provide excellent fishing. If you like tailwaters I would also recommend the Miracle Mile section of the North Platte above Sinclair, WY and the North Platte Grey Reef section below Alcova, WY ( 30 miles south of Casper). Hwy 14 west of Cody, WY follows the North Fork of the Shoshone for 30 miles or better, you will find excellent fishing there, just be cautious of where you step (snakes).
A must stop on you way west is to fish the Green River below Flaming Gorge Reservoir in Dutch John, UT. This is all BLM land from the dam south so access is no problem. The first 7 miles goes through a 1,000-1,500 ft canyon and is referred to as the aqurium. BLM has constructed a walking path from the dam all the way to the first take out called Little Hole, so it is pretty easy to get away from any crouds if you are willing to walk a little. Lots of public camping in the area. If you are interesting in seeing Yellowstone NP then I would recommend that you pick up a copy of Nate Schweber's book "Fly Fishing Yellowstone NP". If you are up for a spring creek challenge, then stop by the Silver Creek Refuge near Carey, ID.