The simple way to get around this is to run your lights at night when you are not using the garage.
Of course, then you would be stuck in the house for 12 hours a night.
Do you HAVE to park in the garage? It seems that opening the garage door would expose your equipment, at least your potting area, to prying eyes (=thieves, yuck).
A 250 watt lamp is not a huge draw anyway.
Check the amps on the lamp, and the amps on the door mechanism, add everything up, and check the breaker that it all runs off. The amps on the breaker should be at least 10% more than what you expect to be using.