Red Rock Country
I live in the west and spend winters down in southern Utah around Zion NP. The park is almost never without lots of visitors. Fall is especially nice there and winter can be moderate.
We have just spent a week in south central Utah at Capitol Reef and on Utah highway 12 and east of the Park on Utah 24. You landscape guys need to go there.
What I want to report is this: I am never in Zion without seeing a serious photo guy. DSLR, bag, tripod and a worried look. In Capitol Reef I saw one guy with a DSLR but he had a long lens and what he may have been shooting I don't know. Mostly I witnessed the arms length guys and gals jumping in and out of cars on the way through the park. Right now Zion is in the triple digits and Arches is not far behind. Capitol Reef was in the 80s although it will get warmer.
If you are considering a red rock experience Capitol Reef should be on your list of good places to visit. The little town of Torrey has several very good motels and three RV parks. Two are pretty good. The Park itself has a wonderful campground in a fruit orchard which is along what is called the Fremont River. It's a creek.
The park has not a lot of improved roads and a state highway runs through it. When we were there the entrance fees were not charged and, in fact, there are no entrance stations. The gravel roads are mostly not awful and mostly not often visited except for the two major canyons.
I have a couple of Capitol Reef galleries on my Pbase site and then there is the area east of the Park which is stark and dramatic. The new galleries are at the bottom of the page. If this is shameless self promotion then I am guilty but the message I want to convey is that if you want a relatively uncrowded park experience then head there. I had my D800 and 24-120 which did me just fine most of the time.
Also not to be missed is Utah Highway 12 which is one of the great scenic drives in the entire world but it takes a couple of days to do it right. One end starts in Torrey.
All that aside, I am not a business owner or a Chamber of commerce shill. Investigate the possibilities and see if it does not fit your style. Incidentally while camped there I saw and chatted with any number of Europeans traveling in rental class C motor homes. None had a bad thing to say about the scenery. They all complained about Utah's stupid liquor laws. Don't let that stop you. Your can still buy a beer and get a drink.