I've got the keepers pegs in my Arctic Tern and they fit just fine. But it may have something to do with my size 11 feet
Have you tried enlarging the footpads by attaching a larger piece of plywood with some padding on it to the existing foot pedals? Another approach could be to establish the proper fore/aft distance on your keepers foot pedals, then attach a nicely shaped cross-piece to both pedals, giving you a cross-bar foot rest. You'd have to attach it after establishing the proper distance because of the taper of the hull.