I have a 25 foot cuddy cabin boat and my wife and I sleep on it all the time. The longest stretch was 17 days in a row last month on a loop cruise mostly in Ontario. Prior to that we did a 16 day trip in 2017, and we've done countless 2 to 7 day stretches on it. I think they are wonderful for the north east US/south east Canada where we boat because the vast majority of the time, nights cool off nicely near the water. Mid-coast US, and anything south of there would be an issue for a typical cuddy because of the heat at night, IMO.
Ours has screens on all the port holes and the hatch, and we have full camper canvas with screens as well, so we can ventilate pretty well at night. We also carry a couple of cheap 12 volt fans that are remarkably effective at cooling us off when we need it.
Ours has a 12 volt fridge in the cockpit and a single burner alcohol stove in the cabin. We use both on every overnight trip. We also have a 17" propane kettle grill that we use on our extended swim platform. The grill can also be used as a burner, so if it's too hot to use the stove in cabin, we have the option of a single burner outside.
Our boat has a porta-potty with pump out plumbing installed so it can be pumped out like a normal holding tank. And as you can probably guess, we use it all the time...
Being a 25 foot boat, our cuddy cabin is pretty big, I am 6 feet tall and can stand up in the middle of it. My boat also has 2 kids berths , thus it sleeps two adults and two kids. When my kids were younger, we all slept on it together, but never for more than one night per trip. There's just not enough room for 4 people to live happily together for more than 2 days on our boat.
Our boat is wired for shore power and has an automatic dual battery charger for the two all-purpose batteries. This lets us run the 12 volt fridge at night in a slip.We also run it whenever the engine is running and for up to 5 hours on just battery power. IT will probably run a lot longer than that on the battery, but I don't like running them down too much as I'm pretty sure it affects their longevity adversely. If we sleep at anchor, we turn the fridge off all night. It does a good job of staying cold all night, so it's no big deal.
My list of must haves for a cuddy cabin boat are:
good natural ventilation
full camper canvas
shore power
fridge
two or more batteries with automatic chargers
trailer
head (does not have to be enclosed)
fiberglass lined self bailing cockpit
We have found that anchoring up to two nights in a row is OK, but a transient slip is needed between anchoring stints for showering and such. That said, we have a good quality solar shower that really helps if we need to anchor longer than two nights. Even if there's no sun, we can heat up water on the stove or grill for it if we wish. I replaced the crappy nozzle and hose on it with a kitchen sink sprayer, which is a vast improvement. Our boat has a self bailing cockpit, so showering in the cockpit is easy.
Feel free to PM me if you want more info about trailered cuddy cabin cruising, I've been doing it for years now and love it.