Though I don't have anything that fits it -- yet -- I did do some narrow ramps on the curb side for lawn equipment or the like. You know, Just In Case.
The trailer also fits the OpenRC tractor
Which is not my design. See
http://makitpro.com/index.php/openrc-tractor/ for the scoop. I changed mine up a bit, used real rubber RC tires instead of printing them and some other details.