here is how i repaired mine http://www.airforums.com/forum...ead.php?t=4753
there are lots of pics showing how big a hole you need to cut, don't skimp on the hole size. if i had to do it over i would have even gone larger!
note of caution: your tank sensor wires are most likely right in that area, once you get the hole started take a look with a flash light so you don't cut any!!
i see from some of your other posts your trailer is also a 1992, so everything should look the same as mine!