My boat has three drop boards and a lock to secure the boat when vacant. When we are aboard the three boards are stowed and we have a single piece (similar to Faster's) which is a frame with screen. This frame has quarter-round trim on the inside into which a smoke colored Lexan panel fits, secured with four butterfly toggles. For privacy I have had a white panel made as well.
Works great, keeps out insects, and provides shelter or privacy when needed.
Catalina 387 #29
Rock Hall, MD