We've had as many as 9 on a 4 cabin cat and never needed a water maker or ice maker. We simply top up on water every 2-3 days as needed and get ice at the same time.

Most cats we've been on have plenty of freezer and fridge space so we keep all our drinks in there and ice in the freezer. Some trips we've never even needed to get more than the 2 bags of ice we started with.

I love having A/C on the boat - not truly needed for the most part in January. Still, we've had it before and used it just for the added comfort and not having to worry about the hatch dance if there was a shower. But we've also been that time of year without and it was very comfortable.