I looked at the first few pics on your journal, it's a 48x18; for some reason the last image made me think it was a 36x18.
For the bulkhead leak problem, I think you can remove it without having to move the tank; there are some sockets? used in plumbing, large enough to loosen the nut side then hand-remove it; new bulk-head, new gasket and some silicon to be on the safe side. It also depends on the opening of the stand where the BH plumbing passes through. Big Channel-lock pliers might do the trick as well. Make sure (if you go this way) to clean the inside of the tank's overflow chamber of any sand for a nice seal of the gasket.