Great feedback!!
I'm not sure about putting holes in the roof! We'll have to chat to a few people about that.
I originally looked at mounting a roof rack onto the top of the camper and it wasn't recommended. The roof itself is easily warped with weight. There is a specific rack intended for pop ups and it has poor reviews. I was hoping that if the bike weight was more supported on the tongue of the camper itself it would eliminate compromising the roof.
Dont think we can swing the inner tube option either! Other than the tandem we will most likely be hauling 3 singles.