OK ... Better pictures of holes in transom to knees.
Hard to see in first pictures you posted ...
So stringer is NOT attached to transom, floor & knees ties it all together ...
Your Buddy with the yellow CVX was done the same way ?
That is some cool chit Doug !
Talked with Scott (Shipwreck) about pourable's .. He thought it was fine to cut top off stringer and pour, then cover with glass.
Also said you could make custom molds with just cardboard and duct tape. Pour and peel ... LOL