Forget the double skeg boxes and just hang the pair off the sides to try it out before you start slicing and dicing.
Be interesting to find out how much more drag two skegs have over one skeg would be the result.

I'm guessing that you could use narrower skegs, and that the increased drag would be negligible.
(a long skinny wing (or skeg) has less drag for the same surface area than a short wide wing (or skeg).

In airplane design biplanes had an inherent problem-partially solved by shifting forward one wing, usually the top shifted forward, but twin tails less so. In water maybe there's no problem.