Exercising generator and A/C after winterizing question?

We use a portable electric space heater for exercising our Onan since it is primarily performed during the camping off season. Both of our gennies are actively utilized during the RVing season since we do more boondocking and dry camping than anything else. No issues on prolonged use of space heaters thus far, sometimes we have 2 of them cranking although both are rarely set to high at the same time.