Have you bought a unit yet, I would suggest a 16,000 btu as I installed ours last year on our 33. I put the unit under the v-birth and we have no noise what so ever. If you intall the unit on top of a plywood base and install rubber gromits that are brtween the ply and the hull, put a good bead of caulk and attach with shallow screws this makes a great base to have the unit installed on and adzorbs the vibration to the hull from the unit. Our unit came setup in a metal base and it also has gromits that hold the compressor off of the mounting plate.
I then ran the supply from the unit to 4 different places on the boat, One to the port head, small 1" hose, a 3inch duct to port bulkhead that then runs into a stainless plentuim box and up the bulkhead 2.5 ft and back out into the forward v-birth. the 2 other supplies are both 4" and run on the starboard side threw the dry locker at the base of the cabinet and one emties into the main cabin on the bulkhead and has a teak cover, this is also where I installed the thermostat, and the other runs thru the starboard storage area behind the setee and supplies the air under the nav station and blows into the rear v-birth.
I do have the water supply that runs from the head fresh water supply and is on a 2 way valve, this is also where the head sink drains, so to winterize the a/c I just flip the swith and can fill the head and the ac with winterfreeze, super simple and no need for another hole. The output from the a/c is different, its a solid stream of water just like the moter outlet it is almost always running water, ours is right above the water line on the starboard forward part of the hull. Champher the hole you drill and the glass will not craze or spider over time.
It was a great investment. Let me know if you need any more information. I did search for several months before buying ours, Wabestco was the best in my eyes for the price and warentee