The Sea Monster didn't need any ballast with either the Saito .72 or the Magnum .70. The nose is actually sealed so you would have to cut a hole to add weight.

I saw the side force generators in your other photos. How do they work?

After flying a Sea Cruiser with sponsons and the engine pod mounted to the wing, I am thinking about another Sea Monster or a Neptune, but modifying it with sponsons and re-doing the pod in between the 2 root ribs. Our Cruiser was built from plans and it turned out a little heavy. For the Monster, the thing is so top heavy without the wing, I have a special cradle to keep it upright in the back of my truck.