My son has 2 large dogs (German Shepherd and large mutt we call "Moose"). He is out in the country, and commutes to work (~45 minutes each way). A simple flap style dog door won't do. (?raccoons, burglars?). Does anyone have experience w/ a door mounted dog door? I'm thinking something w/ a security feature and dog collar that opens and closes when one or both dogs want out while he's at work. Anyone have good experiences? Bad experiences? thoughts to offer up? tia