Your Center of Gravity should be located 0-50mm from the rear of the front sponsons. I like to place my CofG right on the turn fin if possible. The further away your CofG is from the rear of the front sponsons, the more weight is going to be on the prop. Without rear ride pads you will want to reduce this weight on the prop.

The turn fin being straight will work to some degree. Once this gets really dialed in you will notice that the right sponson may be bouncing or lifting in corners. A curved fin will hold the rigger on the water during the turns.

Actually the motor mount distance I forgot to mention is from the rear. Basicly 1/3 from the rear is absolute minimum. If you could get it to work some where around 1/2, this would be optimum.

The largest problem I see is lack of power in the motor and packs. If you really want to watch this thing fly and be on edge while doing so, you will have to reconsider motor, esc, and cell options. Power is needed to get these hull to run dry and out of the water, especially in the rear as you have noticed.

A cheap route would be to go for a Feigao 540 7s motor, an 80A ESC, and 5000mAh 25C 2 cell LiPo. A prop that would work well would be an X430.

Ryan