[69hugger]

Depending on the filler neck design, you could use a pressure washer or take it to a coin-op car wash & wash it out. Between the filler and sender ports, you can reach most of the inside. Use the soapy setting, swish it out, then rinse it. Do it for several cycles.
Then either set it in the sun to bake out the residual moisture, or hook a shop vac up (using the hose on the exhaust side) to the filler to blow it out.
I did this process with my stainless tank & after a few hours of airing out with the vac, there was no fuel smell. It needed welding, and this worked well.

Good luck!!