Yep, When I was poking around online looking up the idea, I stumbled upon this YouTube video of someone doing exactly that.I think a lift gate could carry toys on the back without taking up interior space in the box. Years back, I thought about military trucks, 2.5 ton and 5 ton with boxes, some have expandable van boxes which would be prima.
If you have the $$ Unicat has a few optionsThere is one with a SxS in a garage that lowers down like an elevator. The challenge with length vs people space vs toy space is a series of big compromises. Do I want my bed to smell like fuel? Is my road into the area so bad that a trailer pulling my toys won't survive? I think alot of folks take the living space and then build/buy a trailer tow the toys. Those toy haulers have been getting bigger and longer for a reason.
I love snowmobiles and I have a new one, but you would not want to start it at -30C next to your kitchen and bed...