Check this out, I pulled out my wheelchair lift and converted the door into a deck that drops out like a drawbridge. I had a welder fabricate the steel, but designed and built the rest of it myself.
First, we had to reinforce the side of the bus, under the floor, to support the relocated hinges. Plates were cut to fit around the floor rails then welded into place. On the outside, we cut steel washer plates that are sandwiched between the hinge and the bus skin.
I cut the skin off the inside of the door so we could reframe it with angle iron. In hindsight we really should have just built a whole new door. Squaring and flattening the old door and working around the existing lock was an incredible PITA.
You can see some of the 2x4 framing we were dry-fitting. I forgot to snap a picture of that step completed. We used 2x4's and cut them to fit all the spaces between the steel, then used a table saw to shave them down to the proper height.
Setting the door in place so it would articulate correctly took some time. We used steel cable and turnbuckles to suspend the deck.
We reinforced the roof with a cross-member
Eyebolts into the rail over the door seems to be nice and clean. (I know, that shackle should be moused)
I used drywall shims to level the 5/8" plywood platform.
Cedar 1x6 decking finished it off. (still need to stain it)
The door weighs about 225 so it's a little hard to lift closed. I'm going to install a winch in the top corner with a wireless remote so I can drop the deck out all slick-like.
The weakest piece of gear (being the cable) is rated to 880lbs (each). I think the deck or hinges would bend before the gear fails though. We put 500lbs on it and it still seemed really solid.
The plan is to not only be my personal little patio, but a pop up sound-stage for festivals and the burn. My first event is Apogaea (Colorado's regional burn) where the bus will be debued as a 3000w sound camp.