i put a tackle box in the opening, i had a sheet of plywood cut on small runners on either side of the walkway,but became a hassle to get over when needed,tackle box easier to move or kick out of the way.
The tac kle box/bag is a good solution if you have one that "fits". I have in the past had a small piece of boat cover material that snapped in place (slow and not much fun to remove, etc.) that was very effective.