I've been contemplating designing and building a rear bumper that has an integral fold down or removable bike tray of some sort......haven't got serious about it though....obviously without the bike on there.....
...not what the OP is looking for...
..and borrowing the neighbor's JoeHauler is pretty convenient.....it's leaning on the side of his house, I don't even ask anymore.
Some have a drop down wheel that supports the load like boat trailer which would seem to work. nice to see a steel frame/swing and aluminum tray to keep weight down.
I'm working with Joe on this.
I think i saw somewhere on ADVrider or EXPO someone with a swing out bike carrier on the back of a land cruiser carrying a 2 stroke. It was custom made. Ill see if I can dig it up.
Instead of a drop down or swing away what about a slide out? Like the style of a fridge slide or bed slide. It could slide back or to the side? Some of the bed slides can hold a pretty good amount of weight I think. I don't have any experience with slides at all but just an idea maybe one of you skilled guys could design.