Check out the Thor Outlaw toy hauler. It does not have bunks but it has a large space for hauling things and it is has a queen bed for that space. I would think it would be easy to install two sets of bunk beds in that area. Two by fours with lag bolts and ply wood bottoms can create so great beds and anchoring to wall should be easy. You can build them to fit the size you think you will need. Then memory foam mattress trimmed to fit. The main living area has a queen size loft that is really quite neat. Then you can have a separate tv area with another bed option from couch and dinette in front area with another couch if needed for sleeping. That toy hauler space has some options that might just fit your needs. I love the idea of a bunk room for the kids. You could even do triples if needed for kids. Good luck.