JRyan, do you have a 2005 without either a wash down, or a transom shower? You don't need another hole, if you have a live well thru hull.
My 2000 has the freshwater transom shower, which I also refer to as the washdown, so no thru hull for that. And no pressure, no volume, so it's a lousy wash down, and a lousy shower.. Do you guys consider the shower to be a wash down? I looked at the pump under the passenger seat, and there is a tiny little elbow, 1/4" at the most, feeding the shower hose. I bought a 1100 Rule livewell pump, with the extra port on the intake, and will replace the existing one next time I am standing on my head under the live well. That will give me the option of a raw water wash down, with its own pump.
I know some of the 228's come with 2 thru hulls in the rear, but I only have one. Before I drilled another hole through the bottom, I would consider either a pick up on the outside of the transom, a scoop on one of the trim tabs, or a Y-valve on the macerator thru hull forward, if it was just for a raw water washdown. They would only share the last 4 inches or so, inside the thru hull scoop, and it is constantly flushed when running, and seldom used for anything else.