You should have a roll cage. There are many vendors that make them and call them sport cages because they can't afford the liability that comes with a failure.
If you are just starting to look into roll cages, you either need to purchase one from a reputable builder or learn about static and dynamic loads, materials strengths, and structural design. I reccomend the former.
Rockrat is on here sometimes and he has a great reputation for building custom cages. Maybe he'll chime in. He also gives a lot of free advice. And he has his own bbs at
http://ratsden.proboards19.com/index.cgi. I know you can catch him there if you want.
You should also ask around 4x4 shops in your area about cage builders. There is probably a reasonable builder nearby so you don't have to worry about shipping and they can build it in your rig.
