LOL, no such thing as a dumb newbie question unless you didn't at least try to search first. <img src="/forums/images/graemlins/lol.gif" alt="" />
Seriously, good question. As has been pointed out, it's possible to do but would be very heavy. ...
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Yep. Bunch of times. I agree. A full under-body would be VERY heavy unless done in aluminum. A guy here in Denver did one in 5/16 6061 years ago. Lighter than steel and did the job just as well.
Bad things he ran into - It's a flaming pain in the rear to work on after everything is enclosed like that. If you're 'wheeling where it gets REALLY hot there's quite a bit of heat build up - part of which ends up in the cab through the floor. It also doesn't do nice things for the longevity of the parts subjected to the extra heat. Aluminum doesn't 'skid' as well as steel on sand stone. There is a trade-off if the rock you wheel on is anything like what you find in Moab. There were a couple other things but I can't remember them off the top of my head. Must have been 10-12 years ago at least now.
IMH(biased)O, I don't see the point unless the vehicle is seriously 'ground clearance deficient' and the trails are beyond the vehicles configured capabilities. Long before I did a full belly skid I'd get the body and frame off the ground. A belly pan isn't a replacement for decent ground clearance and it doesn't do anything for break-over, either. This is just my opinion, though, and there are variables that would justify the opposite. I think. <img src="/forums/images/graemlins/ignore.gif" alt="" /> <img src="/forums/images/graemlins/smile.gif" alt="" />
Hazy, "flying debris"?!?? OK, now you're starting to scare me. <img src="/forums/images/graemlins/scared.gif" alt="" />
Edward