Jack you know what I told you about the rear hatch on the transom drop down panel. Make it big! much easier to work in there. Those are 4 TH Marine latch's you see
On the livewell. You said you want to be able to remove it.
Unstead of putting it all the way at the back. Move it foward some. This will help get the weight off the ass end of the boat and also create an island.
If you've put mullet in a livewell before you know how they have a way of jumping out sometime's. With the island setup at least they will fall on the deck and you will still have them. Sometome's they will jump out and over the side to be lost if the livewell is close to the side of the boat in someway.
This is my inlet with the 3/4in Seacock and the drain is the 1 1/2in seacock.
You could have the drain where it comes even with the deck. A flush plug goes in when you remove the tank. When using the tank a large barbed fitting screws in when the plug is removed. I have the Kodiak 42-2. The fitting's are all below deck. I'm not planning to remove the tank. It will sit just in front of the NASA hatch you see in the floor.
No offence ment capt_chuck but I would never do a thruhull X-ducer like that.
Here's mine. I built a box to perfectly fit the X-ducer and glassed it into the hull.
The B-60-20 is what you will want, but it will not go in the keel. It's made to go out to the side of the keel.