I’ve slowly been working on building a Honeywell burglar alarm panel (a Vista15P/20P) into part of a Pelican case for travel. I can just stick up sensors where I need them temporarily (a PIR, a glassbreak, a couple motions), and then use an ECP bus decoder (like the old AlarmDecoder board[1]) to kick notifications and alerts out where they need to go with an LTE-connected miniPC/Pi.

When I need to secure an area (eg, vending at a convention at a hotel, locking up the room with stock), I can just pop down the Pelican, plug in the keypad (which doubles as the RF transceiver), stick up sensors, and I’m off to the races.

[1] http://www.alarmdecoder.com/