Hmmm, that sounds like it might work for me. I could use the beach wheels that will come with my boat ("CatTrax") and put a single length of tube or square bar forward from the center point to the towhitch. A brace or bracket could support the forward beam like you stated for the dart setup.

My tilt trailer is pretty simple...a tilt bed sitting on a wide wheel base trailer. The bed is offset about 2 feet while down, so I have to take care while passing through gates, parking it etc. I raise and lower it using a 2 ton cable winch mounted on a post positioned just in front of the fore beam, cable connected to the tilt bed cross beam. Once raised, I attach a couple of steel posts under the high side of the tilt bed...these take the load while traveling, not the winch. I've pulled the whole thing quite easily with my VW Rabbit!

The problem I have with the overturned boat type tilt trailers is they cannot be used for launching...something I may not actually be needing soon if I get this dolly thing sorted out.