Four in an inside cabin is cozy. One bed pulls down from the wall to form a bunk bed. Another bed is a trundle - pulled out at night forming three twins close together taking up all floor space. There will only be storage under one twin bed. Could maybe leave top bunk down and store extra items there. Chances are he'll be so busy exploring the boat that he won't need his guitar. If he's really good, he could win a free cruise at the talent night. How often will he really use it? There were movies that interested my boys and the magician was really good.