Thanks for you input guys.
Talked to the folks at CruiseAmerica and they've confirmed that there are solar panels which act like a trickle charger for the auxiliary battery but that I couldn't really count on them to run the furnace blower.
She did state that if we didn't have an electrical hookup, that we could expect the auxiliary battery to eventually run out sometime during the night. Someone would then have the run the engine of the motorhome for 30 minutes or so to recharge the battery.
To me that sounds like a noise violation of the various "quiet periods" which are imposed at the campgrounds, at least to my limited understanding of RV etiquette.
Moab shouldn't be a problem in reality; we have Deadhorse which is wide open for right now for the dates we want. And so is Zion for electric hookups which is where we would go on the way there. Its places in between. Would like to visit Capitol Reef (in all my Utah hiking, I've never been!) and I think the kids would get a great kick out of Coral Sand Dunes State Park. Neither of those places have electrical hookups unless I do the KOA/commercial route, which might not be a bad compromise for 2 nights.
The other option is to forget SE Utah and just go to Southern California. We could then 'try out' RVing in Joshua Tree or Anza Borrego area (where night time lows should be manageable) for just a 3 night rental, and spend the rest of the time visiting the San Diego zoo, Legoland etc.
Last questions, and I know its basic but you guys have been great:
1. Parking in a small town like Moab in a class C (probably will rent 25 ft at MAX). I love the coffee shops and would probably like to take the family to dinner/breakfast on occasion. Where the heck do you park when you hit these small towns? Do you just find an empty nice sized lot and then walk around?
2. We really aren't RV'ing for the financial benefits, so we may need to bail because of weather or comfort issues and stay in a hotel for a night or two. Are these places usually accommodating to the size of RV we are going to rent for parking?