This may not help but I have to ask if you have a storage building that you can lock for big things like mowers and bikes? Possibly put a heavy duty padlock on as well? Along with good exterior lighting? For a problem like that maybe even some cameras.
Also sounds like your area is BADLY in need of a neighborhood watch program or something. We have a few tweakers and generally worthless human beings around who like to steal, I have seen evidence of them trying to steal my riding mower (tried to pry out the ignition switch), cut the steel cable lock I have on my shed, and just prowling in general.
Other than that I keep my valuables in the house close to me, definitely nothing outside that I want to keep. Lock things up as well as you can. Force them to work or make as much noise as possible to get something.