Oh, got it. That was one of the possible mounting locations, however there is nothing to mount to in that area really; I have some other things already mounted in that location as well, so it wasn't ideal. Also, I wasn't too keen on drilling yet another big hole in the firewall.
I am not concerned with mounting it under the fender but I understand your points. I thought through this pretty hard, researched it, talked to Rich at FASTman, etc. The reality is that this box was designed and built to be exposed to the environment on rock crawlers, sand rails, race cars, and even boats; so I am pretty good with it being in the fender. That said, it will be on top of a plate, so it will not take a direct hit from anything, sure it would get wet but again I think it is designed to take it. If this were not the case, I would not have even considered it, but looking at it and talking to Rich as well as others, I am ok with it. If I am wrong, I will come back here and state it publically...
The better point here is that I am not altering anything that cannot be fixed easily and if this doesn't work out and I end up wanting to move it inside, I still be able to.