We had a man just last month purchase some land for his RV and after he had it all fixed, he was told it was illegal to live in an RV in our area. Check and double check the local county regulations before you invest in any money. I live in the country
Second, there are tons of ways to insulate your RV for winter climate. Check Facebook, they have a Winter RVing site with tons of help and ideas. The secret of course is insulate, insulate and then insulate some more. This will help in summer also.
There are also some great tiny homes that are built on RV frames that might work for you also.