I agree with Boone.....if he comes that close that often, he's killable. The one's that wont come any where near your equipment and/or leave no sign are the tougher ones.
Canids can't help themselves when it comes to checking out other canids, scent marking, etc.
I'd consider bringing in a coyote turd from another area and using it downwind of the sets he's digging at. Blend your trap in first, sweep or blend in local duff to make it look like its been there for years! Use a backing that's already there, don't move anything around. Short grass tuft or rock or whatever. After trap is blended to look exactly like the whole area, THEN place your turd. If you place turd first, it will grab all of your duff from sifting and sweeping and not stand out as much. It can be old and white or black and fresh, it matters not. I like the extreme colors because they stick out. Here in wet New York State, I don't find many white ones like I do out West. So, around here, mine are usually black black.
If adding anything to that turd, I'd only add good urine. Just a few drops. In theory, if he's coming right by there, he will see it before he gets to other sets (assuming wind is still right) so you don't need to blow his nostrils away........
This method works great not only for smarties, but dummies to!
MZ