How much are you looking to spend on this trailer project?
Have you considered a single wheel trailer similar to my trailer project?
http://ecomodder.com/forum/showthrea...ler-26997.html
There are a few companies that have single/swivel wheel trailers available.
Swivelwheel ECO is about $900 and would be a great platform to work with. They can handle up to 500lbs. They use a torsion suspension setup.
SWIVELWHEEL-ECO
Toy-Tote has dual wheels in a swivel wheel setup which I would love to git. They have the highest weight hauling in the swivel wheel setup. Keep in mind that these trailers are not anywhere close to being cheap. I'm not sure on what sort of suspension they are using on their setup.
Toy Tote - Toy Tote
Smart-Trailers should be based in Lakeland, Florida which might be close to you.
Smart Trailers — Guaranteed Never To Jackknife!