Sounds like most of you all subscribe to the 'Paranoya Mean Destroya' tune. All we have is a 12 buck Harbor Freight driveway alarm to tell us when a vehicle is in the drive by the house. and I agree with Mossy, dogs are basically useless as watchmen. Our 'mean' dog would go for a ride as well and probably leave nose prints on the glass. The big deterrent is my NRA sign in the front yard and my Trump sign. If you can read, you know where I stand on stuff.
The dogs that give me the most concern are the little ones I call 'ankle biters' The little ones seem to be the most agressive in my experience. The big 'guard' dogs are really docile. Big bark and no bite.