I have a vague feeling I was aware of this. And elsewhere I've heard of old carriages being used as temporary – and occasionally even permanent – housing (not camping!) for railway employees in Poland right up to early 2000s.
On a different note, a couple of weekends ago I was camping (in a tent!) at a place which included an old goods wagon very nicely refurbished. Lovely site and the wagon looked quite cosy. Ex-Southern Railway, if the label I saw is to be believed:
https://orchardgetaway.co.uk/avalon-carriage/