So here's what I've been doing with my summer vacation. My last date for logging time on the speedster project was 6-11-13. The plan was to put a couple weeks in and finish up the trailer to have weather tight storage and free up shop space.
The roof is .060 EPDM (rubber) over thin plywood and the upper side walls/door skins are prefinished .032 aluminum. Skeleton underneath is mostly 1X1 16ga tubing with some 2X2 16ga floor joists and corner posts. Floor is 1/2" treated plywood. I'm going to get it weighed soon and will post the empty weight later.
It pulls well behind my 1/2 ton pickup. It has the feel of pulling a small boat. The weight is there but not much drag resistance.
Overall I'm quite pleased with the results other than actual cost which went totally out of control.