Just the skin is adequate under your feet, be it PVC or coated nylon. A second
layer of skin material under you heels works well also if it's a concern.
With PVC just glue it on.

For a footbrace, you can re-position the cross section nearest your feet so
that it's used as a footbrace. You likely will need to make it slightly larger
than the original ( email me on this and I'll provide you new offsets).

Another option is to use a removable closed cell foam block placed against a
cross section ( look in the Folding kayak Builders Manual under Sea Glider).

You can use adjustable footbraces such as Yakima attached to a stringer, or
something as simple as homebuilt setup. The alum frame Sonnet's use a single
tube that snaps onto the chine, but a wood version is just as easy to
construct. As I recall, David from Hobart, Tasmania came up with his own
wood footbrace solution. It too is seen in the Folding Kayak Manual under
Sea Pup.

Even though you are building a wood frame kayak, there's lots of cross over
info in the other manuals, especially the Folding Kayak Builders Manual as
it's the oldest and most detailed of the three. I suggest you read all three
manuals before you begin. The wood frame construction is mostly based on the
aluminum frame kayaks.... A point lost on many builders.

Regards, Tom