I'm in the 15" or deeper crowd, though I have considered building a pocket and sponsons on my boat and getting an extra 3-4 inches at the cost of some speed.
I consider navigation skills to be underrated. There are a lot of places you can get to if you learn your boat well and know what the tides are and know the area. Sometimes all it takes is to stop, pole through some 6" water, and hit the channel on the other side and resume your trip.
I think bass boats are stuck on the side by side paradigm simply because they evolved with side consoles MANY years ago, and typically you had 2 fisherman, and as tournaments developed, they simply amped them up for speed. The amateurs simply copy what the pros do, and buy the same types of layouts without thinking about versatility (or the absolute beating your back takes when running through rough conditions while sitting vs standing). FWIW, the bass types aren't so often worried about reading the water as a bay boater is, as lakes are FAR more reliable about holding the same bottom features year after year.
Bass boats these days are 50-70mph boats, top.
Most bay boats are more like 30-50mph. Frankly, I'm not in a hurry.
Bay hulls are designed to take rougher conditions in open water, generally. That completely goes out the window if you get a cat type hull or a run-shallow hull, though. You'll get the beating of your life running a trans-cat across a shallow choppy bay.
All in all, there are several center console hulls out there by several mfgs that have pockets or partial tunnels that will run in maybe a foot of water, and still have an appropriate hull shape for running open water. There's no need to max out the HP of your boat unless you plan on taking half a dozen people with you regularly, but don't necessarily get an outboard near the low end of the recommended range, as you will have more issues getting on plane loaded, and you will be running closer to WOT more of the time, which negates your fuel savings. Best fuel/speed balance is usally around 2/3 max rpms, but your absolute best fuel efficiency is almost always something more like 6-8mph, not even on plane.
Used isn't a bad way to go. Just inspect it well.