Ask them to add. They should be able to do them. You don't need the rubber on the inside. A 2" or 3" section of pipe added on to the back at the drain hole with a flapper. Stick a small zinc tab on it. That pic fishing fanatic Jason posted is the idea. Defiance has them on their boats at the show as does Katana Marine. Look at Wooldridge and Lifeboat for a different style even easier. A pipe and a sock that is sewn up flat that slips over the pipe and clamped up with hose clamps. The other side is larger flaired out and has a seam sewed down the middle to keep it flat. Water goes out from the inside but the flatness prevents water flow in. The flap will move up or down with the wave action. Thunderjet makes a good looking boat. I too almost bought a Hewescraft from Tom and Jerry's in 2008. I got my used 2004 NR Seahawk instead. $8000 cheaper. Spent $8000 at the old Monroe Sportsman's Show to outfit it. Rods and reels, pot puller, shrimp and crab pots, life vests auto inflate, Scotty DRs. That shit adds up quick. And then throw on new electronics for another ten grand. Your choice of the 4G radar might be over kill. Look at the 3G and talk to Lowrance about the real world differences. You won't use the added range do to the right of your radar mount. While your at it stick an Autopilot in the boat. You will be glad you did. Enjoy!