[dsargent]

Daniel - is this aftermarket tank poly or aluminum? Many of the aluminum tanks have screw flanges on them, and that would mean that the fasteners let go or fell out. If it is poly, you definitely want to lighten up on fuel regardless. What type of access is behind the tank in the sceptre? I own a 20CC and the tank is a bitch to get to. You may want to tug on the fill pipe or grounding wire to try to drag the tank back forward but you also need to get access to refill the aft end with foam and/or a bulkhead of some sort to prevent future migration.
You can also contemplate putting in a deck plate to get at the aft end of the tank if there is no other access but do cut carefully