Alan:
I don't know if there will be a gas shortage this winter or not. I kinda doubt it.
Nonetheless, I don't like the idea of storing gas. Todays gasoline does a lousy lob of maintaing its octane. After about a month, its pretty much useless. Second thing to consider is condensation. Gas thats been sitting around in the winter tends to accumulate alot of condensation. Obviously not good. Essentially, your not using fresh gas. My next main concern would be the tank. If your planning to run your plow off this stored gas for a few days, plan on getting a huge tank or a ton of smaller ones. Now you have to find a place to store all this gas. Maybe you have a shop of garage or something. All I can say is you better talk to your fire marshall. I would hate be toned out to a fire involving that much gas w/o its own fire supression system. I'm not sure what the rules would be, but I am sure they are fairly strict and should be followed for your own safety.
I'm not trying to shoot down your proposal. These are just some of the issues that might arise. Obviously, it can be done. However, just keep all these things in mind.
Eric