I would be interested in hearing more on this myself... Its going to take removing the rear bumper cover and adding in some special bracing on the rear bumper material... then cutting a peep hole in the rear bumper. A class one flat bar type would only require a small 1/2 x 2 inch hole. Class one is under 200lbs tounge weight and less than 1500 lbs total trailer weight.

It would be some serious work to remove the bumper and investigate the possibilities... I wouldn't even know where to start.