I installed a fiberglass enclosure in my spare tire well, and removing the spare tire brackets is a PAIN! We had to drill out each of about 20 spot welds, and then knock that thing off. Then I used some metal weld mix to fill in the holes in the bottom of the well. It took quite a bit of effort and time. I think it would be really hard to build a fiberglass enclosure without removing the spare tire well brackets though...good luck. I'll have pics posted on a web page soon with a step by step of the install...
