There is always prayer..........

I don't think you can do much except make the place secure from the opportunist, if someone is determined to get in they will ( speaking from experience ).

Our finca is alarmed, sends texts when the alarm goes off, has cctv and is visted regularly by a friend who lives a mile or two away and a contractor that farms the olives. Unless it is occupied 24/7 I dont believe there is a guarantee.