I wish it could be that easy. Its not the tank since its stainless steel. I did have a problem with the filler tube (up to the gas cap) that was steel and was rusting from the inside. Changed that out to aluminum, rubber hose attaches it to the tank. The two dissimilar metals are not in contact so theres no corrosion going on there either. Had the tank out and filled and flushed it with the hose twice, There are baffles in it so I couldn't get to the corners but I think I got everything (maybe not).
I think the problem lies within the inline filter. There is a flat pleated stainless steel screen inside of it about the size of a quarter (maybe 1" - 1 1/2" square). Filters down to 40 microns. I think at that size it doesn't take long to plug up, hence the question of what size is everybody else using?
Panavia
Pretty much no to most of your questions. The longest gas sits in the tank is over the winter but I use Stabil (marine grade) and the Startron additive specifically for the ethanol. No gunk in the tank that I can see at all. The only question that I'm not sure of is I used a cork gasket around the sending unit hole. I don't think thats a problem for gas because when I took it out the last time it was all still intact.
I don't know... but its very frustrating.
This new filter
http://www.summitracing.com/parts/SUM-G1503/
is supposed to be here tomorrow so I'll be trying to retrofit that in. Will try to keep it as low as possible so it will gravity feed itself to help the pump with the suction. Compared to the size of a quarter this should give me a ton more filtering area and hopefully a little longer driving time between filter chokings.