You may want to figure out what you want the system to do, either discourage them from bothering in the first place, or catching them in the act of committing the crime.
I would say the sprinkler and an alarm, with visible security cameras and motion-activated spotlights would discourage most would-be thieves.
If you want to catch them, then you do away with those and just set up cameras and go with the silent alarm and maybe some traps that hinder a quick escape.
If you do both, and you get a thief that still goes for it, you have an even better legal case against them, but it may be a lot of trouble and expense and all you may get from it is a small amount in civil court to repair the damage they caused. It's pretty tough to do even if you have receipts and documentation and can prove what repairs cost, and of course you have to pay all the legal costs up front and get nothing if you lose.
The best thing to do is just keeping all the vehicles in a garage so they're out of sight and not a possible target in the first place. If that's not possible, then the silent alarm is the way to catch them. Just remember to sneak out the back door and around to the driveway to catch them in the act, if you bust out the front door they will just be off and running before you're even close. Don't bother with any formalities either, just shoot 'em in the legs or something. That should keep them from running, and also keep them from coming back. Do this once or twice and word gets around town, don't screw with your ride unless you don't mind not being able to walk ever again. Sounds harsh, but that's the only things some people of lower intellect seem to understand.