For outdoor security I was thinking maybe those motion activated deer hunting camera's might work or I know they have IR camera systems pretty affordable now..might detour anyone that see's they are being watched....
I was also thinking braided fishing line is really strong, nearly invisible and maybe could be used with christmas bells around the perimeter for a warning/alarm type of deal...
I also was thinking you could maybe set up a speaker and some kind of motion device, set with a recording of some nice shotguns loading and cocking..... i know most that hear a shotgun cocking wont stick around to figure out if its real...lol
plant some nice poisonous nettles and cactus or thorn bushes around your garden...will make it difficlut to get to..
buy a lion "cause nobody messes with a lion man" from the movie Grandma's Boy.
Here is a DIY for building a autonomous Paintball sentry gun...might be a fun project and would scare the bejeezez out of anyone not expecting it....
Autonomous Paintball Sentry Gun
lol...wouldnt that be funny to catch on security cams...!! lmao!!!
These were just a few things that came to mind while floating by your journal...!!