The stinger will be cut down to about 2 1/4"...so yes that is roughly about 10% of the hull length. The rudder will have about 1/2" to 3/4" taken off of the bottom (I am also rounding off where the bottom and leading edge of the rudder meet. That will help cut down on some unwanted lift and drag.

The motor will be placed right around where the front of the hatch opening is (just about in the middle of the hull) and the lipos will be placed in the rear...closer to the flood chamber wall. With that setup, my CofG is between 28% and 30%.

One thing you should think about doing (if you have not done so already) is add a plywood doubler. Epoxy it to the inside of the transom and then seal the wood with epoxy. This makes for a stronger transom and also gives you a place to use blind nuts to mount the hardware with if you would like.

One more thing...you will need to drill some holes in the flood chamber towards the FRONT of the boat...in the deck AND OR in the side/ underneath. This will help let air escape from the flood chamber so the water will rush in and the boat will self right more efficiently.

-Kent