Before heading to the Bahamas we considered the same type of systems. None seemed viable and in the end we did nothing, though we did carry a loaded crossbow!!! . Also, we never had the slightest hint of any problems. There are a couple of simple things you might consider. The easiest is to spread some (stainless) tacks like roofing nails around typical boarding locations. Another is battery powered motion detectors for inside the cabin entrance areas or battery door alarms. Both are inexpensive and easy to fit. I think the biggest risk is being robbed while ashore and neither system will help since you will not be there to deal with the intruder thief.
The other thing to consider is that your dinghy is probably the most prized target. Need to chain it and/or hoist it up at night.