Great work!
You could install scupper caps that use a Ping-Pong type ball to close as water attempts to flow in...not very aesthetically pleasing, but they work. I installed a pair on the splashwell scuppers on my Outrage 21' to keep the water sloshing around in the splashwell while trolling for salmon and trout to a minimum. I used to routinely have at least a gallon of water sloshing around, which was quite annoying to listen to for hours on end.
Also, assuming these are current pics, your trailer tires look low.