That's given some useful ideas. We may be replacing a broken off gatepost soon. A bit of heavy gauge box section with an artistic cap might be able to include a covert camera plus a motion sense light off axis to the camera so no reflected glare. The light would give a reason to cut a trench for an armored supply cable. The trench could also contain a bit of cat 5 in a duct to serve the camera.
Since my first post I learned this evening the hall in the next village had a similar problem and installed high speed bumps which the boy racers lowered suspension cars cannot cope with.
We'll probably try that first 😁