Lovely varnished(?) internal rear deck!
And you've come up with an interesting concept for your rowing footrest.
On Proteus, we have two rowing positions:-
For the forward position we followed the official footrest design. Noted your concerns about "six or so holes in the bottom" - Our forward footrests are bonded not screwed. They have not given any problems.
For the aft rowing position we wanted a clean deck, for similar reasons to yours, but decided to go for a detachable raised footrest bar.
It fits into two "do-nuts" which are bonded to the inward faces of the bulkheads/buoyancy.
When not in use it is stowed in the port locker/buoyancy.
You'll find images and a sketch on the "Proteus" page of the website.
Find it via "Known Uk Morbics", "Proteus", then look in the central section headed "2) Details, Quirks, Mods," (etc).
The “Extra Hatch” (for stowage of long items in the port side buoyancy/locker) is the previous slide in the sequence.
Let us know how you get on.
ATB – PW.