I second the wired camera recommendation, at least for a few critical cameras.

WiFi cameras are vulnerable to a de-auth attack. It's fairly trivial now to make a device that will kick all WiFi devices off of a particular network. It's not so bad if they record internally and are inaccessible. If they can be reached, once someone is inside, or if they don't record, they can be bypassed completely, or stolen.

This does all depend on the level of protection required. Basically, are you worth the effort of targeting, or is it just to dissuade opportunistic attempts.