We put our bikes inside the camper
We also considered an external bike rack, but found the bikes can be easily loaded (with a little patience) into our x17z. We have never scratched or otherwise damaged our interior while moving the bikes (2) in or out. Once inside, we cover them with an old blanket and throw another blanket between them. I don't feel there is any more effort involved than using an external rack. Obviously, they should also be braced against movement.