Garffin
Are you 4'8'' tall?
You're right about floorboards. All small boats and many larger ones have seat lockers with loose tops. The best idea is to put hinges and positive catches on all lockers - just buy ss piano hinge and cut to size. Imagine your boat upside down and what can fly around, hurting both itself and you. Bungee cord will not work if there are heavy items in the locker. Tapered plugs are good but also make sure the seacock is durable - no gate valves and if it looks flimsy and you can't afford to change it make sure nothing heavy enough to break it is nearby if loose in a seaway.