access hatch in Nacra 5.8 hulls

Hi
I'd like to build the following compartments in my nacra 5.8 solid fibre glass (Not sandwich) hulls:
- a live bait tank
- 2x insulated compartments, one for food, the other for the fish caught.

To make the operation of these compartments easier, I'd like to replace the 150mm wide circular inspection ports with larger rectangular access hatch.

The hull's deck is 30cm wide down to 25 mm wide at the transom.The dagger board are located 1/3 of the front beam to rear beam. .

My questions are:

1/Where should I locate the hatches? Is half way between the dagger board and the rear beam best? what about half way between the rear beam and transom? or fore of the front beam?

2/What's the maximum size for the hatch without compromising the structural integrity of the boat?

3/ how much reinforcement should I put (around the perimeter of the hatch)?
I have 936 gm double bias Fibreglass Cloth. Is a double thickness of this cloth with polyester resin 10 cm wide around the compartments reasonable? Should I worry about the loss in flexibility of the hulls with such a reinforcement?
Thanks for your help.