I wanted to do the same thing on Precision 28. I bought a regular 110 volt
room a/c and set in on the deck just forward of my cabin hatch. I then had a company make me a sort of tent out of sunbrella and clear vinyl that attaches to the front of the a/c and funnels the cold air into the cabin. I remove the a/c before taking the boat out and lock it up in my dockbox. If you want more info just e-mail me. Good sailing!