Just have a BT dongle on an active usb extension cable positioned centrally in the loft. Then use eventscripts on the Mac to detect my phone (and the wife’s) approaching the house (turn on outside lights / announce events via Sonos as I enter the house). I can change the house profile based on who’s phone is detected. I find it a passive way to detect occupancy as my phone is constantly polling the BT without much effect on battery.
Vangelis