The E85 we had in the tank was in There from October last year. When we cranked it over mid January the car fired first hit no worries. I'm not sure if all this "can't leave e85 for more than 10 days bs comes from.
Considering your fuel tank is a sealed container it should be able to sit there for ages before it goes off. If you left your tank open, I'm sure it would be a different story.

__________________
2016 Subaru Outback - Work Wagon
350NM of CVT Goodness
Pit Crew, shit talker.