You're not going to catch many coons in a diving set. Pocket sets in stream banks will catch a lot of coons but those are designed more for using footholds than conibears.
Don't take this the wrong way, but by refusing to use footholds or to set conibears on land, you are basically setting yourself up for a really rough season. ESPECIALLY for a first year trapper. You just don't know the nuances of the animal well enough to use them against the critter to make it work with your limitations. You've limited yourself to conibears in some sort of water set. There goes 99.9% of your chances of catching any kind of fox or a yote. While pocket / cubbie sets with a conibear will work cut into stream banks, you need to worry about water levels constantly fluctuating (at least I do). You're not going to get many coons to dive into a pocket that's underwater.
If you've got lots of muskrats or mink around, you're grinning, but if you hope to catch a bunch of coons or any foxes, you're limiting your techniques too much in my opinion.
"Knowing when to shoot and when to wait is one sign of maturity in a bowhunter. Be patient and pick your aim point carefully." ~ Randy Ulmer
"I suppose it's the way of hunters. We are very odd fellows." ~ Peter Hathaway Capstick