I have built an all aluminum trailer for my Tornado...it's a tilt trailer 'cuz of the 10' beam, but the basic trailer frame construction method could be used for any boat. The frame is 2x3x1/8" T6061 Alloy with a tongue beam of 3x3x1/8"...all bolted together...no welding (which will destroy the temper of the alloy). I used a light duty (~1000lbs rating) Torflex axle (no springs to rust!). Whole trailer weighs under 400 lbs, so with the boat & wooden storage box, the total weight is easily less than 900 lbs.
We plan to offer all the brackets and plans as a kit, with the alloy sourced locally to save shipping costs.
Here is a link to the prototype I made:
Tornado Tilt Trailer Mike.