We have the same camper as yours. I bought some anchors at Lowes that were made to use in luan to hang things like towel bars and the like. They are rated for 120lbs each in plywood so its a similar application. I hung a 48" towel bar with 2 on each end and it feels solid. Granted its not that thick of a wall but if you had shelves with support under them towels aren't all that heavy.
You could try a stud finder to locate anything solid to screw to as well. Mine will locate wood, steel, and aluminum and it was like $25, also at Lowes. Good luck either way!
2016 Jayflight 27bhs Elite
2015 Chevy 2500HD