I did it too, (sounds like a song)
I have a 40.5, and did a really neat install as I'm a little obsessive in that regard. First of all, I installed an extra through hull fitting with its own seacock valve. Oh, stop moaning all you guys out there, there's a good reason for it. Basically, when I'm not using the pump, I shut the seacock off, so I am not risking a major hull leak. You see, the proper installation is to use a fresh water strainer before the pump, and these guys can and do leak. Furthermore, the pump needs to be winterized properly, which means disconnecting the input and output hoses. If you just T off an existing through hull, you can't do that. I installed the through hull in the midships locker under the aft berth, and the inline strainer in the same locker on the starboard wall. The pump is actually mounted on the aft wall of this locker, but on the other side of the wall; e.g in already dead storage space. You must run a #14 minumum wire run from the panel, on a dedicated breaker. The pump has a nasty inrush, so this is required.Next, I installed a flange mount Perko male hose unit on the port rear transon locker wall. This allows for easy access. A good tip is to buy Garneda roll up hose, as this will reach anywhere on the boat from there. In other words, don't bother putting the fitting in the anchor locker, just run a hose from the cockpit. I also have a 10 foot section of hose availabe for quick cockpit spray down.My kids spill cokes at the rate of 6 per hour.Good luckArt