Install the fuel tank backwards. Fuel will still pass thru the clunk as the pressure tap will still do it's job. Run (epoxy) some 1/8" brass tubing along the inside of the fuse (plumbing) to carry the fuel to and thru the firewall, or anywhere else you want or need to send fuel or pressure. Leave about 1/2" of brass tubing sticking out to attach fuel tubing. A second length of brass tubing can be run as well for the vent/pressure tap. Keeps fuel tubing to a minimum and saves room to boot. What's the worst that can happen?