I was just about to ask a similar question. I have a 31' Prout with a 5K BTU unit in a cut-in to the cockpit. I had the unit on during a very hot week here in MD (this last week). I bought a thermometer that shows highs and lows for indoor use and it was up to 93 degrees, with the AC on! This is not good for my cat.
So now I am looking for alternate solutions. I'd like a 10K BTU but they are substantially bigger, which means cutting a bigger hole in the cockpit and finding a new housing (currently has a nice little shelf/covering area that would be a real shame to lose).
I have been thinking of this:
Amazon.com: Whynter Eco-Friendly 13,000 BTU Portable Air Conditioner, Frost White (ARC-13W): Home & Garden
And just setting it up to somehow drain into my manual bilge area, then pump it every night. But the bilge area is in the head and the place that I could vent (small window in the berth) are about 10 feet away from each other.