@OP,
Sounds like your mission has two goals --- To find a retirement location AND to convince DW she'll be happy fulltiming there?
You've been a member here for 10 years. What's your history of long distance RV trips for extended periods of time? Why the concern about DW being part of the cross-country drive?
Assuming your rig has a generator, or you'll be staying at CG's with electric along the way, the heat/humidity won't be an issue. We have been to the Myrtle Beach area many times over the years and heave been quite comfortable with the RV AC running. No different than in a S&B house.
If it were me in your situation, I'd bring DW along for the RV trip so you can decide wright there and then if fulltiming is for her or not. Then, you can make your retirement decisions together, knowing full well what the real situation is.
IMO, it's a lot better to deal with the situation up front than to have one (or both) of you miserable, based on an uninformed decision.
