I'm wondering how you guy's boats are different from mine. My 3250 has a raw water input via a pump, and to drain, I merely pull up the pipe in the middle (has a soft tip plug at the bottom) and it drains out via gravity to the side. I know it collects water via rain and so do the engine cover hatches.
After I learned that my faithful canine's

fur was clogging the scuppers, I would hose down and clean the "tracks" where the hatch covers would lay and this kept the scuppers clean. Since I keep my boat in a slip and have shore power, the bilge pump handles any runoff (but check that pump filter for fur regularly!

)
If I were keeping it on a trailer, I would opt for the low tech mat or cover to keep rainwater out. With winter coming, this is a bigger issue and water freezes. Maybe some antifreeze in the bilge?
Bruce
Loose Rules V1998 Pro-Line 3250 LXi's, B3's