: The barbs on the tee-nuts are thicker than the plywood and would poke
: through. You could just nip them off with diagonal cutters and the little
: nub left would have to be hammered or pressed into the plywood.

: Some builders have concerns about the rails flexing if not backed with wood.
: I have not had any problems. In fact some complain about the foot pegs on
: the plastic Keepers popping off from too much foot pressure. I think I use
: knee pressure against the deck rather than a hard foot press. A solid
: strip under the rail would ease the concerns but the hull is curved and if
: backing is done with plywood the rail would still have to bridge the
: curve. So a carved or an epoxy-buttered-up piece would be necessary to
: fully back the rails.

: The epoxy is bombproof to secure the tee-nuts from spinning. If you want
: studs just epoxy them to the tee-nuts when you glue on the tee-nuts. Or
: just epoxy flat head screws to countersunk plywood washers and forget the
: tee-nuts, much cheaper. I did not want the end of studs sticking out
: through the nuts on the footbrace rails to chew on my ankles.

: There is a trick gunsmiths use to know when a screw is too long for a
: bottoming hole (common for mounting scopes). Screw the screw in through
: the attaching part until it bottoms in the hole and note the position of
: the slot on the head of the screw. Take the screw out and shorten it by
: grinding some off the end. Screw it back in through the attaching part
: until it bottoms. Note the position of the slot, it should be will be
: different than before. Repeat removing and shortening the screw until the
: slot no longer changes position when re-installed. A that time the head of
: the screw will be bearing on the part and the end of the screw will no
: longer be bottoming in the hole.

PS
The bolt length is determined before gluing on the tee-nuts. By assembling the the bolts, tee nuts, plywood washers and footbraces and gluning them on as complete assemblies, not only are the bolt lengths determined the spacing between the bolts is assured.