I think Lulu has explained how most retirement villages work. A lot of them have a waiting list for units. When you decide to move out you can't just sell your unit on the open market, it must be offered to someone on the waiting list.

My grand parents skipped the retirement village stage and went directly into a nursing home so I'm not sure of all the details for a RV although we did look into it until my grandma deteriorated quickly.

My advice would be to choose a couple of villages that you know of and which you think your dad would be happy in and to give them a call, it shouldn't be too hard to find out who manages them. At worst, you could always visit the management office and have a chat to someone.

Good on your dad for recognising that he can't live entirely independent any more. I hope his transition is smooth and he finds somewhere he loves!