If they are shooting deer here is what Missouri is doing and have caught a great number of idiots shooting from roads. They set up deer decoys made by the University of Missouri that have remote control and move their heads tails, etc and film these guys shooting at the decoys. Here is the link

http://www.youtube.com/results?searc...rch_type=&aq=f

It does suck to see what is happening nowadays but wardens are out there and like you said they have to get caught first. We have a lot of spotlighting around here and there are reports of wardens getting the upper hand as spotlighting is fairly easy to see and apprehend someone at night. If you get a trailcam they do make some that have an infrared sensor and do not flash so that maybe a possiblility for you. Other than being on the stand each day to catch these bums there is nothing that can be done unless you know the art of boobytraps which could be another way to capture the idiots, you could claim it was for hunting and I'm sure the game warden would agree.