Foaming gunnels

[CHANCE1234]

Has anyone considered or done this. In redoing my deck on a 20SF, i've noticed there to be some decent flex with my deck removed when i push on the interior gunnels. i realize that replacing the deck will firm this up once i reglass it to the sides but would there be any benefit in pouring foam through various holes (rod holders, etc...) to fill up the emptiness between the inner and outer liner of the hull? Would this help making the deck more solid too since everything would then be connected, all be it with foam in the gunnels.

Or is it an invitation for water to enter through all the holes typically placed on the top cap and to trap water there?