I don't. When I fill my onboard Onan, it gets a full tank with Lucas Fuel Stabilizer. Never had a problem.
All my lawn maintenance equipment that sits for extended periods of time get a full tank with Sta-Bil whenever I put them up for storage. For example, my aerators (Honda and B&S engines) get a full tank of fuel and Sta-Bil in early November. They typically sit until the following September (10 months). They crank after 2-3 pulls almost every time. Never had a carb problem as well.