I've been studying the options lately as well. I can't speak specifically to your coach, but in a general sense you might be a candidate for flex panels glued down. The biggest issue will be positioning so they aren't shaded by other fixtures up there, like the AC unit.
It sounds like you're looking at standard solarvoltic panels which may create quite a challenge for racking. I don't know that I would want panels sticking up on a van. Are you looking at 12v panels? What's your target output? Have you considered the flex panels?
Chris & Sherry Brown -
2005 Itasca Sunrise 31W - W20 and 8.1
2021 Chevy Spark Toad