Gas valve shut off for engines when in storage?

I store my Corvette for 6 months during the winter and I would add Gas Stabilizer in the gas tank then I would run the engine for 20-30 minutes. Just follow the directions on the bottle. Never had a problem come spring time. I also do this on my lawnmower, generator and snowblowers. Instead of taking out the battery on the Corvette I would put a trickle charger on the battery. If I was in your situation I would do the Stabilizer in both tanks.