Ernie's idea is a good one, to zone the greenhouse. We had friends in Tok who had a small greenhouse (maybe thirty feet long or so) and they had a wood stove in the center section where they grew things like sweet potatoes, tomatoes, and peppers. Then the two end sections were used for things that could take cooler temperatures. I don't think they were growing year-round in it, but maybe you could in Wasilla.
I would think you should look at a combination of ways to heat the greenhouse. You wouldn't likely be able to heat it completely with just one thing, like solar or wood or methane or a
compost pile. But maybe with all of them together (especially use some rocket stoves and run the flues through the growing beds), plus some extra mass and night covers, it would be feasible. I don't think you'd be able to grow warm weather stuff in the winter, but you should be able to keep it warm enough for cool-season greens.
You also should grow seedlings for people -- you could do custom grow-outs. A lot of the greenhouses around here make most of their money that way. Lettuce and salad greens are also big sellers and are high-value crops, and don't need a lot of heat.
Kathleen