Well, thats kind of ugly..
Since you have it down, brush off any loose rust and treat it with a rust converter. I use Ospho which converts the rust to a black paintable surface. Once treated with a rust converter the rust will not come back or creep.
Treat any place where you see even light rust on the outside of the tank with a rust converter..
All rust converter treated areas must then be topcoated with paint for maximum durablity.
Consider painting the entire top of the tank with a durable paint like a rubberized bedliner.. Harbor Freight believe it or not carries their own bedliner paint in a can that is pretty tough. Do not use Rustoleum bedliner, it is junk, it is nothing more than textured paint, it is not rubberized and scratches easily.. I would suggest using bedliner on the entire outside and even the tank straps for good measure.. I live in the rust belt, steel tanks tend to fail on the tops and where the tank straps touch the tanks..
The pix showing the inside looked OK but if you can see any spot inside the tank that has signs of rust you may wish to consider using a tank liner system..
Por15 products makes a tank liner paint system that holds up well to Ethanol.. It is a multi stage/product were you must use a Etching/cleaner then the actual tank liner.. With Por15 tank liner products you need to read and follow the instructions to the "t".
