In the winter:
Leave your furnace running (on low) at all times when you are gone. Otherwise you pipes will burst and water will freeze in the dishes left in the sink. It will start freezing at around 25F, not 32F.
You will go through propane like crazy. You need more than 2 30# tanks, 2 additonal tanks are good but a bigger 100# tank is even better (if you have the place to store it when you don't need it)
Need to get a heat tape and insulate your water hose well *before* it's 25F outside, dark, downright miserable, snowing maybe, and your water hose has been frozen for 3 days and you cannot take a shower. Then you still must not forget to leave a little bit of water dripping because it will freeze even with the heat tape at the point where it enters the camper (it cannot be insulated there). A light will help too, a bit, but all of the above needs to be done and maybe then you get to take a shower when it's 18F at 6AM.
32' is the minimum unit I would consider for full-timing. IMO. 35' is really better, towing issues never-mind. That's *my* expectation, not for everyone.
Space is critical and how you store your stuff. I have a lot of clothing, misc. stuff so I have to be super neat, which I am not.
You will miss internet and phone big time. Look into alternatives. Which are expensive. Have to learn about wireless internet and stuff you had no idea existed while you lived in the "world".
The biggest problem with full timing is not the unit you are in but the place you are at... makes the biggest difference. 25' vs 32' doesn't matter as much as that.
There is lots more but that's the essentials. Pretty much common sense but becomes obvious when you encounter it.
It's a special mindset you have to have... definitely not for everyone. You will have issues, the older the camper, the more issues. I've been relatively luckly because I haven't had major failures of anything (fridge, univolt, furnace, etc) and the failures I've were largely the result of my own incompetence... but I've gotten wiser....
Justice - When you get what you deserve. Mercy - When you don't get what you deserve
Grace - When you get what you don't deserve