We had a 1999 22 cruiser and it had the optional factory floorboards. These served to level the cockpit floor as the hull has a shallow "V" in it. As you are able to remove these floorboards, you can see that there is, at the most,
2 inches of space at the deepest part of the "V" tapering off towards the sides.
I don't believe that the newer ones would have raised the cockpit floor much more than that. So my thinking is that there is negligible wasted space under there and it would be too small for any practical use.
Cheers, Tom