Invest in a trail camera. About $150. screw it to a tree, set it on infrared, block out all of the little lights with tape, and wait. Check the card, print pics, take them to the neighbors and say, "If you don't replace the firewood, I'll turn this in."

Worked when I had a miscreant snooping on my property. He hasn't been back.

We're just starting a build project as well. (Actually started it a year ago but took a year to get a DOT permit for utilities).