How to flush toilet from behind a locked door? "Lock-off apartment"

CaptionI've lived in a newer apartment complex for the past 3 years. I was looking for a 1-bedroom, but the owners offered me a "lock-off" 2-bedroom apartment while it was still being built. 2 bedrooms/bathrooms, with one bed/bath locked for a future roommate. Never got the roommate, but I do enjoy the bigger living room and kitchen...The main issue is that the toilet/sink in the locked-off bathroom periodically runs dry, and I have to have someone come over unlock the door, physically flush the toilet to keep sewer gas from coming up the drain. This is never convenient and it usually ends up with me breathing sewer smell for a few days until I get someone in.tl;dr Is there any (non destructive/permanent) way for me to flush a toilet from behind a locked door? A string with a 3M-style hook that they might let me put on the bathroom tile that I could pull underneath the door? Something automatic?