We are also planning a trip to the canyon lands in Southern Utah - but in June. We were there many years ago, BC (before children), tent camping, so we also don't have very much recollection of the campground facilities for RVs. I do remember that it was so beautiful, I told DH to let me close my eyes for a little while in the car because I was tired out from seeing too much beauty!!
Anyhow, in planning this trip, I did find this site in my searches that was interesting:
http://www.utah.com/database/campgrounds/?id=130
The BLM and National Park campgrounds can be accessed on the nps site:
http://www.nps.gov/state/UT/index.htm
FWIW, we are also visiting Mesa Verde Indian ruins since it is only 2 hours from Moab, UT. Our kids will love it. Their visitor site is:
http://www.visitmesaverde.com/
Sorry I can't offer any personal experiences camping with our TM, but looking at these sites might help. I hope you have a great, beautiful, LONG trip!!