Your dual tank Ford set up sounds like a good idea. I've thought about ways to heat up B100 when parked at home as well as on the road. If you get some resistive heating type pipe wrap from your local hardware store, you might be able to do what you want fairly cheaply with a little bit of elbow grease. The pipe wrap would be the kind that prevents pipes in your house from freezing,
When you're parked, 120VAC could power up your fuel line pipe wrap system directly to keep it warm. When on the road, you might be able to hook up an inverter to get 120VAC from your 12VDC. If you permanently mounted the inverter in your truck, all you'd have to do is move a plug in from the household 120VAC to your 12VDC/120VAC inverter when you drive. You'd have to be careful to make sure the current draw isn't too high for the 12VDC/120VAC inverter system.
You'd obviously need to have 120VAC for the system when parked with the engine off or your battery would get drawn down pretty quick. You'd probably still need to heat your B100 tank with coolant due to the amount of heat that would be required to warm the tank sufficiently.
If you do try a system like this, I'd be careful to make sure the heat wrap system was thermostatically controlled and/or had a safety shut off so things don't overheat. Although, I'd guess during extreme cold, having enough heat will probably be the problem. Insulating the lines somehow would probably be the key to making things work sufficiently at cold temperatures.
Another option would be running your coolant lines to the heated tank right along your fuel lines that are to be heated. If you had both fuel and coolant lines wrapped up in an insulated assembly, that might work fairly well once the coolant was heated up.
If you want less home grown types of solutions, check out Arctic Fox products at the link below:
http://www.arctic-fox.com/
