OK. I think the general recommendation would be to try to put it somewhere well out of reach, rather than enclose it - the more sturdy an enclosure is, the more it will affect signal strength OK - greater sturdiness doesn't necessarily equate to increased dB loss, but you take the point, I hope. Definitely plastic rather than metal, anyway!
You could look to put the AP in an enclosure and cable to antennas outside - but that would mean different, more costly antennas - which would then not get the protection of the enclosure either.
They could use a cluster of MV cameras to keep an eye on the AP (and each other)...? 😁