A madcap idea I once had, yet it seems to work ok.  During the winter months when the bikes are not going to be used, I zip tie plastic bags on the vent tubes of my enduro fuel tanks.

I first fill them to the top with fuel dosed with Stabil then bag them. 
Theory is that when the area the bike is in warms up, the small amount of air remaining in the tank expands and inflates the bag slightly.  When it cools, it draws air from the bag back into the tank.
This way, the only moisture drawn in or out is the small amount trapped inside the bag when it was originally half inflated.  The ethanol is not drying out the air inside and then drawing fresh moisture in.

Obviously this is only good in low temperatures and the fuel has very low vapour pressure.  Mine is in a unheated conservatory.  A heated garage at room temperature (sheer heaven, i have less salubrious appointments) would probably raise the vapour pressure enough to blow the bag.

I have used the bags twice now and noticed that the smell of fuel in the conservatory vanishes.  I have seen the bag in various states, more inflated and less so over various days, although never more than slightly more than half filled or less than maybe between half and a quarter.  I try to fit them half filled so it has room to adjust either way.

If the conservatory heated enough for the vapour pressure to butterfly the tank, the bags would burst first and there is no way would the tank vacuum with 15 celsius of temp range with a half a litre of air in the bag.

I think it also helps with the loss of volatiles from the fuel, although that is Stabils job in the first place.

Madcap scheme.  I think I have an idea for a flux capacitor next.

Sounds like a great idea to me!

Just don't light any candles or anything that could get close to the bags...