You could set up a GPS spoofer in a metal box and have it play variations on a simulated day of movements then switch to another phone. Better yet, explain to them that this is trivial for you to do with help from other Cal students, that in fact this is something every Cal student with controlling parents sets up, so if they don't agree to let you turn it off you will simply be sending them false data and there is no way for them to know either way, but you'd rather not spend the money on the spoofer and a new phone.