I found a Hustler brand small jon boat trailer on CL, I had been looking for 6 months or more and had to jump on that one. Lots of yakers use the HF trailers, you can swap the wheels out for larger/taller ones that are better for interstate rolling. Make sure you pull the bearings and re-pack 'em as several comments indicate they come light or low on grease straight from the box. Put a flat floor on it with a couple cross bars/uprights and you've got a double decker. The HF trailer should work fine as the trailer is not really holding any payload per say, just make sure the bearings are maintained.
GO BIG ORANGE !
I meant to behave, but there were just way too many other options available at the time.