Neil, it seems like the main consideration here is that you need at least one FTE (on an annualized average basis) to qualify a building for LEED-NC, according to the Minimum Program Requirements. If you have less than one FTE, you can still do LEED but you can't earn any IEQ credits (but you must still earn the IEQ prereqs).

Sounds like you can do that with security people, and count drivers as transients.