Think this was a typo, taking in numbers in the rest of this OP. Think she is 55 years of age at present (not the 65 she typed).
I have a friend who has lived in his caravan with his partner for some years now. Of course, problem is where it is going to be situated. He owns the field in which is is based.
Surely, living in a caravan (if a proper place for parking it can be found), is similar to those living in the Park Villages, (or whatever they are called), where there are stationery versions of large caravans. However, they do have such things as mains water and sewarage and electricity there.
Just having 'a caravan' is not going to provide any sort of home, unless a proper site for it can be found, which will, of course, cost in terms of rents, etc.
Not sure of the reason for the nasty comments about her mother, and what relevance that has to the question. Unless she is saying that she is, at present, her Mothers Carer, and her mother would not be able to continue if she was not there for her.
My goodness, twenty years is a longtime to look forward - Even if my estimation of her age is correct she will then be in her mid-70's. Who knows what the next three or four years is going to hold for us all, let alone two decades.