In a 2004 Subaru Outback H3.0 (LL Bean) is there any way to repair a leaking fuel tank without removing it?

My fuel tank is leaking. On a 2004 Subaru Outback H3.0 (LL Bean) you need to remove the entire rear axle and exhaust components (and probably a few more things) to remove the fuel tank.

My Check Engine light is on. The code is 0442. The exhaust stinks like one of those old 2-stroke engines or worse. And the mechanic lifted my car and showed me a wet spot around and under the fuel tank. So I need to fix this in order to keep this car. He said the pump is somehow good, but the fuel tank has a leak.

I thought I’d heard of some kinds of rubber inserts or some "arthroscopic" repairs by going into the gasoline nozzle and patching it. Does anyone know anything about repairing the fuel tank without removing it from the car (from the inside of the tank or something like that).