I took my camper for a 7 week adventure a few years ago. Hit the Mighty 5 plus Grand Canyon. Stayed at a number of state parks/BLM campgrounds. I chose not to do much boondocking due to recent flash floods and being a big chicken to get stuck haha.
These offered great spots:
Red Cliffs...
Remember despite our little 550’s being so small we still are too big to travel Going to the Sun Road past Avalanche on the west or Rising Sun on the east (though good spots on both sides to unhook if needed unless of course you are staying in the park then it’ll be happy at campground). Enjoy...
Find a site with electric and grab a ceramic heater. I have mine at just around 50 degree mark to kick on and add a little warmth to the camper at night. Was perfect this past October as I ventured home towards snow!