If their airspace starts at 3000', then why not just fly over at 1500-2000' (depending on how built up the area is - I agree with Backpacker, I go over my house at 1300' but then it is not really a "built up area") and do whatever you want? You could call them out of courtesy to let them know what you are doing, but no clearance is required and they probably wouldn't thank you for messing around in their airspace when there is no need to.