See if you can borrow one
The suggestion to see if you can borrow one to try first is a good one. I had a friend selling one, and I tried it for my O'Day 25. It was very cold that evening (Texas, mid-summer, but it was at night). We went to sail the next day, and I ran into a surprise. It wouldn't fit down the forward hatch. Decided to put it in the v-berth by bringing it in through the cockpit and companionway, but it wouldn't get past the bulkhead dividers seperating the v from the salon. I put it in the salon for the rest of the day, and gave it back that night.Instead, I bought a "Krusin Kool Portable Air Conditioner". It's basically a Samsonite suitcase with an a/c unit inside. The cooling pump is connected via hoses and dropped over the side, so all of the condensation is (supposedly) pumped overboard with the water used to cool the unit. (Ours still leaks a little).It cools VERY well (I believe it's 7500 BTU), and sets up quickly, stores easily. As an added bounus, we've been able to carry it to use on our Coronado 35 as well, although it doesn't cool the whole boat (we're installing a central unit this year on that boat).It's a bit pricey ($1000 new), but you can probably shop around and find a refurb or used unit