Could you not build a slight crown in your deck with gutters outboard and scuppers/drains in the aft corners?
Perko makes some nice ones with rubber flaps to keep inflow to a minimum.
Issue is these hulls, being small as they are, it's tough to put the deck high enough to avoid letting water in when people shift weight around, while low enough so little stumble won't put you in the drink.
Flaps, ok sure, but a crown isn't gonna help when one fat guy makes it list.