Need a little clarification here. Does it sit all summer unused or is it driven a few miles every weekend during the summer? Is it driven regularly during the winter?
If it sits all summer without any driving, you could jack it up, remove the wheels, spray coca cola or phosphoric acid on the rotors, let it sit for a couple of minutes, then wash off and replace the wheels. This puts a coating of iron phosphide coating, that looks like corroded aluminum, on the steel, but it will keep it from rusting and its very thin so it will rub off quickly when the brakes are used.
Otherwise, don’t worry about it.