Re your option #1 route from Dinosaur down to Grand Junction...did it once, wouldn't want to repeat that drive.
We weren't even towing and were in just a Class B Sprinter with plenty of power to haul us across Douglas Pass. But some steep grades and switchbacks earned a spot in my "roads to avoid." Other people might scoff, but I still recall the very unhappy faces of some other campers towing big trailers when we stopped for a break halfway at a rest area pull-off. Nice scenic view, though.
I'd backtrack as you described in option #2. There's a KOA at Vernal, by the way. Nothing special, but it was fine for an overnight.
For campground in the Black Hills, I loved Game Lodge in Custer State Park. One of the best SPs in the country IMHO. We spent five days there as a base for touring the area.
