There is a disadvantage to producing reverse tools- if you make a good job of it, people will ask you to make some for them too. Don't say you weren't warned!
At least with the lost foam method, you have the valid excuse of it being a one-off.
A chap I know had one of those little 'Searcher' subs built to the Graham Goodchild plan which was published in Model Boats back in the '80's. Thats was made of wood, although he used plywood instead of balsa. He also made it a wet hull with a little watertight box, made out of- balsa, with an acrylic lid! Never saw it give a moments trouble, although he only used to dive it down a couple of feet. It was a good and fun little boat to drive.