Easy, shut bangshee off, put in trailer, forget about it. Next race, turn on fuel and fire up! I shouldn't be a smart ass but I had a Blaster that was NEVER purged for three years. Little bastard never had an engine failure. I may go a month between it running and haven't had a problem. I purge mine at the end of the season and usually spray fogging oil in the intakes and exhaust port. I store the engine in my basement of the house.
Unless you are purging with gas that you know doesn't have ethanol in it, your just putting a different type of alky into the motor anyways.