How to bond a cockpit liner to hull sides

I'm currently designing a boat that will have a "cockpit liner" (I dobt inow if this is the proper term) but basically the deck and inner gunnel walls are in one piece. The tolerance between the hull sides and the liner is going to be about 5/8" to 3/4". What is the best way to bond the sides on these 2 pieces? Do I make a ledge/dam and pour foam? Or should I core the sides of the liner to make the tolerance smaller and use bonding putty? Is there another alternative? Thanks! Attached are ours of a stick built version of the hull, and a mold for a liner similar to what I'm talking about, in an effort to explain.

 

Most don’t bond those areas, it’s bonded to the hull bottom (stringers), then again at the gunnels.

Foam can expand more than desired in some areas and warp the hull and/or liner.

Putty can shrink and do the same thing, especially in that size of a gap.

 

Yes those were my concerns. I really don't want any rattle, and I want to achieve that same solid feel of a stick built vessel...

 

You won't get that feel. This article talks about the three typical deck to hull joints: https://www.sailmagazine.com/diy/sealing-the-hull-to-the-deck

 

You may like to experiment with PolyStyrene granules.

If you get a bag of "beans", the sort that you put into "Bean Bags", reports are that surprisingly, they mix very readily with epoxy.

The resultant lightweight, but quite incompressible mix would not expand or contract, but might serve as a great filler for the gap between liner and hull.

Might be worth a test.