If you have less than 15ft, depth of the line don't matter in my experience. I run mine right across the top without weights if outboards aren't an issue. Makes the line much easier to run, and less issue with snags.
I would look for the "cleanest" water with the best current (assuming you're on a slow moving system like mine) and lots of cover. Log jams are awesome for holding cats. Forks are good too.Take a rod with some punch bait and a slip bobber and go fish a bit. Use that to hone in on the areas that produce a few fish. I've also had luck running some yoyos and limb lines to test out an area and justify running a line.
I've had some funerals and surgeries going on this past week, but this evening I'll try to actually get some pics and videos up. No promises, but if
@swampsnyper ever gets his vessel license we might be doing a youtube trotline contest. I have a feeling that guy might know how to put the "here fishie fishies" on some cats.