I used these pieces of 1.5mm x 3mm Wood for Battens. I laid it across the Bulkheads, right along the Bend of the Bilge, where the Hull bends down towards the bottom.
It takes a bit of fiddling and adjusting, which is why these Clamps that I made from Paper Clips worked so well.
What you do is to lay the wood across the Bulkheads until you “feel” where the wood lays across it in the most natural way… With minimal bending.
As an aside… While I was doing this, I discovered a pretty radical flaw which I had to correct with my File.