Matt: what you need are called "meths" often. You should be able to get it easily in any hardware store.
I don't understand why you need any heat since you will be perfectly warm in your Zpacks tents. You will be perfectly dry in your Zpacks rain jackets and gloves, and you will sleep well in ---- well you get the idea.
Have a spectacular journey.
I am off to hike for the weekend in the rain this weekend.
Dara