There was a posting in the touring forum a while back about a boy who built his own camper trailer and travelled a good distance... with a 3 speed bike.

It was featured in a 1940's Popular Science issue.

Love the OP's images... you will need a chain stay mounted hitch as a seatpost mount will destroy your bike and a more aero shape and lighter materials will make a huge difference.

With larger wheels the trailer will ride and roll better but sacrifices some wheel strength, could also offer some under trailer storage ideas to keep things as low as possible.

Don't forget to add some levelers to the camper.