I have a couple Ring cameras, but I do not have the Ring alarm system. My mailbox is close to the street and it is impossible to trigger recording if someone approaches my mailbox without recording every car that drives by. I was thinking I could put a door sensor on my mailbox to let me know if someone opened the mailbox and then just record on that event. Our neighborhood is having problems with people stealing mail. If I bought the door sensor and put it on my mailbox could I have it trigger my camera to record? Do I need to also purchase the base unit? I don’t think I want any other alarm components, if I have to buy the base unit can I get it alone or do I need a full system? What is the smallest system available? Thank you.