Wow that is hard to say. Are you positive there is no pin hole there for fuel to seep and eat the tank?
Best you could probably do is sand down the paint there and re-primer and paint. At least it looks like a hidden location.
The ride IS the adventure. The destination is just to get gas!
strip the tank down to bare metal and apply a coat of "RUST MORT". It will neturalize the rust for 10-15 years. I use this stuff often on older cars. After you get tank to bare metal and treat the surface just prime with an epoxy primer or self etching primer and prep to paint. Remember a paint job is only as good as the primer underneath it.