There are plenty of cheap, small, discreet and effective tracking devices available today. If you own an item worth a substantial amount of money that is easily and regularly stolen - and you're constantly worried about it being stolen - then fit it with a tracking device.
Small, easily transportable, but valuable items of construction equipment are regularly targeted for theft - but tracking devices have been quite successful at recovering those stolen items.
Simple signs stating the area is under hidden IR camera surveillance are also effective in theft deterrence.
And you can always buy cheap trail cameras with camouflage markings, and mount them in areas leading to the high theft area, to create a record of those who carry out the theft, or who often "case" a place, prior to the theft taking place.