help designing an inland huntin/fishing boat.

If your boat does everything you want it to except go fast, then keep it as is. Get a second boat for speed and experimenting.

Mud motors are notoriously slow and heavy. They do one thing well and that is to go through shallow mud. If your water is deeper than six inches and not that much mud, you'd be better off with a conventional outboard and vented tunnel hull. If not much mud/vegetation, then a jet motor might also be a good option.

If you're set on keeping your mud motor and putting it on a different boat, keep a few things in mind. A longer boat will be better, I think, for jumping up on plane in shallow water (will keep the transom from diving as much); however, a longer boat will not turn as tight if you have a lot of slalom runs. Another option would be the transom pods - e.g. Beavertail. A narrow beam will ride much better in rough water and be more efficient, but will take longer to plane and be less stable of a hunting platform if you're building a duck blind on it (although you could probably go a foot less beam than you are now and have about the same stability with a flat bottom). Maybe a Panga style would be a good option if you need to cross rough water and then get shallow... it will still pound at higher speeds, but will be quite comfortable at sub-planing speeds, as will most flat-bottoms with pointy bows.

A tunnel will not gain you any speed - it will cost you speed. It's only good for getting the prop up in shallow water. You can regain some of the speed by venting the tunnel, but that's really only an option for an outboard with a good tunnel prop, not a mud motor.

Most boats have ribs on the bottom for 1) strength and 2) to keep the boat from sliding in turns. If you have plenty of prop in the water, stability in turns is not much of an issue, especially if you have any deadrise. If you have a motor jacked way up on the transom, you will slide through the turns - takes some getting used to, and you introduce the hazards of chine-tripping, swapping ends, etc.

When all else fails, go with one of the boats from the mud motor mfrs. - they've done a lot of the homework for you.