I saw a trailer that one guy built that had only one plank, which was located right under the shrouds, at the balance point of the boat. The trailer had a clamp that grabbed the front crossbar. He trailered his boat (Dart18) around like that for many years, and claimed that it supported it well.

He used to use an ATV to pull it across sand down to the beach for launching.

While using this design as a road trailer is questionable, it sounds like it would make a nice short haul trailer or dolly.

By the way, what kind of tilt trailer to you have? I have been trailering my Tornado flat, since I usually only go about 5 miles and the lanes are 12 feet wide. I am looking to build one of the trialers that carry the boat on its back.