Jim,
Those recommendations are based on the alcohol being wood alcohol -
METHANOL (highly corrosive to brass, rubber, cork, etc.)... Where the
alky is ETHANOL (corn whiskey) you can be more relaxed about alky
remaining in the tank even at the 5% level... So, while your
assumption that if you dilute sufficiently you can leave it is right
on, you will have a bigger margin of safety if you can find ethanol
based gasahol...

denny - in Michigan where we can get alky free mogas...