Bill,

That is where my concern comes in.
Rigid structure means heavier and probably triagulated in order to take the heavy loads at a single point. Kayak or canoe SOF is not designed that way.
Making the structure that rigid "might" make the whole thing heavier than a solid skin. It will certainly take away the simplicity of SOF.

I did make the assumption that this would be with outriggers and more sail.
No outriggers will naturally limit the loads that can be imposed (won't take much to knock the boat on its beam ends).
I guess there will still need to be triangulation, just not as massive as I was assuming.
Some of the canoe sailors get by with essentially clamped on thwarts and almost useless mast foot support - except that it must not be useless since they go sailing and like their setup! So much for my assumptions.