Bobber:
The section of white PVC pipe trick works for me but one thing I would add is that you have to give the coon a reason to want to stick its hand in that little hole, too. The trap itself or small hole itself doesn't have much eye appeal...something that you gain with a traditional dirthole or pocket set made in a good coon location. The white pipe I think brings back the eye-appeal piece missing in this set. I think it is the pipe with at least a 4" inside diameter...so that the trap slides in well into the end of the pipe and the trap face plate ends up flush on end of the pipe. The trap model I own has the swivel/rivet attachment on the side/bottom of the trap and sticks out a bit. I cut a 1/2" slot down about the same length as the trap from the end of the pipe and that slot allows the chain to slide down in this slot.
In early part of season with open water, I plan the pipe with trap just out in water and have the end with the trap facing the bank trail if the trail is right along water's edge. If not, I plant the pipe right into the side of the bank with enough white sticking out so that it can be seen by passing coon.
Load the inside of that pipe up with loud goodies like fish oil, fish bait, lure, etc. Again, give them a reason to reach into the little hole.
When I am not using a pipe section, Dig a hole in side of bank like a pocket set but add some eye appeal around that little hole by taking water and splashing it up around the sides and then smoothing the wet soil so that about a 2' round section around the little hole is really slicked up smooth. Load the hole up with bait and lure and set the trap in the hole. Don't laugh at this one, but I've also used a can of that Christmas tree flocking spray and sprayed the slicked up area around the hole snow white, so to speak, so that the little black hole really stood out against that white background. The white spray stands out very well against the creek bank and can be seen for quite a ways away from the set. Looks goofy as heck but it works well for me escpecially with these little pet-resistant trap models.
You can paint the face of this trap white also and that makes the little hole stick out better especially against the soil of a creek bank. Keys though I believe is (a) sets made right on location, i.e. literally right on still smoking hot trails (not old trails that were good in fall but have been since abandoned) (b) eye-appeal of the set, and (c) a reason for a coon to put its foot into that little hole.
Jim-NE