maybe bait it . I wouldnt bother with the locking gas cap - if you loose the key, or break the key., or the lock gets frozen with ice... to me alot of bad could come out of that at the wrong possible times. if had my share of frozen locks. at a gas station , low on fuel, when im suppost to be out plowing, on an item that you cant use a cutting tourch to remove....id pass on the locks..besides, they wll just go take it from your mowers.
id bait it, but get cameras. im looking at a set as i speak , ties into your computer, records motion. $400 bucks for 4 cameras. almost cant go wrong.
few motion lights would be a good investment also