Think defense in depth. Multiple methods to make it difficult to gain entry and steal and that require time and effort for the thief. These scum want to get in and out quick. More time equals more likelihood of detection and confrontation. While a camera is good, it's primarily forensic for after-the-fact evidence, so make sure it takes good quality images.
Most important thing, when you're not there, lock it up. My garage has a locking roll-up door, but I also have it padlocked to the pavement when it's closed. The bikes inside are all secured to a rarely used aluminum extension ladder with cables and padlocks. The bulk of the tools are in the house.
. . . rest have no identifiers that I can use to prove they're mine.
Make a list of the bikes. Take pictures, including of the serial numbers. Email to yourself for a timestamped document. I also put a card, with my name and contact info in the bottom bracket and seat posts of all my bikes.