I haven't read through the entire thread in detail, but I want to commend you on mocking the bumper up out of cardboard before building anything. Sometimes it's easy to get lost in CAD and never make a connection with the real world to get a proper sense of proportion. There's nothing worse than getting really excited about a design, thinking everything is perfect, and then being totally disappointed after working so hard to build the real thing.

Keep on making mockups and don't stop until you are happy with it. It's a lot easier to cut & tape than grind and weld! <img src="/forums/images/graemlins/cheers.gif" alt="" />