With all the aluminum body panels on modern cars & trucks, PDR (paintless dent repair), also called "glue pulling aluminum" is becoming very common.
The process works by adhering a pull anvil to the panel with adhesive, pulling, inspecting, repeat etc. etc.... until it's gone. All done from the outside, with the paint intact.
I don't do it but expect there would be plenty of shops who would do in any larger metro area. The gear is portable like windshield repair, so in a hangar should work fine.
This is all assuming you have a small "bird size" dent to tackle and the tank is structurally sound.
Might be less pain than building a new tank.