Hey, Bill!
We actually pushed our big trip out from CO to Canada until mid-August because of snow reports and the like. Our first stop in the Flat Tops just north of Glenwood Springs JUST opened up so far as I can tell. Problem is...while it may be wonderful the first two nights in CO, it's going to be really hot across the low areas in WY. I think we'll manage with the route I've planned out.
One thing I'll warn you about through TN and the like is to pay close attention to the temps and the real feel. When we went out to CO last July we camped the first night in TN and it was awful. Especially with both the dogs in the RTT. I had a cordless 10" fan on the cross bar and all the windows open and it was just bearable. I canceled our HipCamp site in Arkansas for the second night and grabbed a hotel as it was a real feel of 110. That's just miserable for two-leggers, and potentially harmful/fatal for Crazy McBitey, and Sir Spins-a-lot.
We want to tackle the TAT at some point. But that's a tough call on when to leave; particularly with potentially insane weather out west! Re: camping, though...we absolutely love using HipCamp as an option. It can be an easy button approach, particularly when hauling a trailer and we can't get much ground truth/area knowledge. Sometimes it helps to know you have a suitable spot waiting for you instead of stressing out and not being able to find one where/when you need one.
Love to your far prettier half, and give the big guy a belly rub!