Lucky! E85 is too far away for me to use it or I would. I was talking to a Fuel Distributor to deliver 55 Gal Drums that I can store and he said that is a bad idea. If E85 Sits too long you need to test the fuel to make sure it is still good.
In a sealed drum I would say about 3-4 months in a cool shaded area, As soon as you open the drum it will start to collect moisture... 55 gallons once opened in a twin turbo car probably wont sit around as long as you think ;)