I carpool. Where we park our cars has a cop going by at odd times, but usually within a few minutes of each other - station is about 1/16 mile from there. I park directly under a streetlight, angled so the gas cap is visible from the street. Hopefully that will help. I don't have a locking cap, as I agree - I'd rather replace $44 worth of gas, (small tank), than argue about my deductable with the insurance company.
At night it's garaged.