I found an article on
Smart car concept trailers. They look really nice. It would be great if they went beyond being just a concept.

I really like the last one.
"In what appears to be way of addressing the lack of trunk space in the new Smart fortwo, DCX has released a few sketches showing the Smart accessorized to appeal to that overly-pursued active lifestyle consumer.
The three drawings (two of which are posted after the jump) include the above boat trailer, a motorcycle hauler and a traveling living space; complete with sink, stove, storage and bed.
While all are intriguing, Smart doesn't intend to build these trailers anytime soon. We certainly like the idea, but are a bit worried about getting stuck behind one on our way up to Tahoe."
copied from the web site. If they are light weight enough, I do not think they would have any problem going up an incline(

).