IMO, it would not help to heat up the fuel in the tank. By the time the e85 makes the long trip through the fuel lines and to the injectors it will be whatever temperature the fuel lines were at, which would be the same as the outside temp.
At times temps here get into the single digits, luckily it's usually just a short winter blast, but I've never cranked my car, even at those temps, for ten minutes.
What issue I do have...above 45 degrees it starts the same as if on gas, between ~25-40 degrees it takes about 3-6 tries to fire off with an occasional fit where I'm wondering if I'll be walking to work,
below 20, even into the teens and single digits it starts with 1-2 short stabs at the starter. It actually starts better as it gets colder
. In my case I know the car starts better as the temps drop below a certain level which makes me think my fueling/whatever maps it uses to start needs fine tuning in certain areas. IIRC, one of the tables uses air temp to compensate, no doubt, mine could be better. What I wonder is if yours may need fine tuning, unlike gas, just a little off w/e85 and it's a bear to cold start.
Anyhow, have you thought about a heat lamp or just a rough service rated incandescent light bulb wedged under the intake? A bulb socket w/pigtail can be had for cheap at the hardware store, plug it up just like a block heater. If you wanted to leave it their maybe make some kind of, 'nest' from a small amount of insulation?