I had the unfortunate experience of being broken into last year. Having a chat to the uniformed people that attended, their recommendation was was an alarm with the biggest MoFo siren you could get inside and outside, to get the attention of everyone nearby. Don't bother with back to base as by the time anyone responds it's way too late, but text alert is handy so you know it has gone off.
In my case, PIR's weren't an option due to pets, so to fit an alarm I would have needed to fit reed switches to the doors and some windows, which was not an easy task, so I went the camera route with a 6 camera system back to a discretely located hard drive. Mount all of the cameras in visible locations where the grubs will see them, and put up signs to show surveillance cameras are in use. That will generally be enough to deter the opportunists. I'm using all Hikvision gear, and on the motion detect setting, I can get 5 weeks of video from the 6 camera's on the harddrive.
I also put a siren box with a strobe under the eves in a highly visible spot. There's no siren in it and the strobe is not connected to anything, but hopefully it's enough to make the grubs think twice ?
Can I suggest sending a PM to Patroldude, he's in the business and has helped a few Myswagger's out in the past (including me) He's based in Rockhampton, but will ship gear anywhere, and will give you the right advise and a variety of options.