A few years ago there was a real problem with theives stealing your tackle whilst anglers were sleeping in their bivies. An early warning system was needed to alert you to anyone trying to make off with your gear.
Rightly or wrongly in my younger days I have poached almost every type of game from woodland and field and on the odd occasion i have triggered off the gamekeepers alarm gun, nothing more than a trip wire attached to a weighted firing pin which falls to a blank shotgun shell. Enough to knock you senceless for a while but more so make you leave in a hurry. This along with memories of carp fishing theives had me thinking of this for your bug out location on a short term or long term basis.
Look on ebay and you can find fishing bite alarms, some as cheap as 3x£10. What we would do whilst night fishing was to run a weighted trip wire of 30lb breaking strength line over one of these alarms, and through looped pegs around the bivvie and fishing spot. This was set up at night without even the guy next swim to you knowing you had it in place. Just like the alarm you use on your carp rods it would sound out if it was touched, loud enough to wake you and sudden enough to deter any would be thief.
I would have thought this is a small enough system to fit in your pocket, easy to set up in a few seconds and would give anyone an early warning system to your camp if out under the stars.
I will draw up a simple drawing of whats needed but im sure most of you can figure it out