Sounds like a regular 5th wheel toy hauler with a dedicated garage is what you need. WE had a Fuzion 342 that fit the bill. 12' garage with 2 queen beds for the kids. Bottom bed made into a dinette for eating and card playing. Close the door and kids had their own area with TV and Xbox. You don't think you want an onboard fuel station or generator, but when you realize the convenience of both you are going to wonder why you would ever want to lug around fuel jugs and a stand alone generator.
The garage is a dual purpose room. Why you would not want access to it would not be practical. Use it to haul you bikes, BBQ and whatever else. Unload at your destination and roll out the carpet, put the door down, pull the big screen door down and enjoy. Toy haulers are a very multi-use trailer and you are going to get more uses out of it spaces than you think.
Otherwise you can just get a bumper pull bunk house TT and put the bikes in the back of the pickup and call it a day. Would be a heck of a lot cheaper.
