I have bought and sold a caravan both by bank transfer and by cash.
In both cases I printed a Sale Note with a short description of the caravan, date of sale, names and addresses of seller and buyer and a space for signatures. Printed two copies, one for each of us.
Do not accept PayPal. Only use PayPal for something you can post with proof of postage because the buyer can claim their money back through PayPal saying it wasn’t received, and without proof of postage you’ll likely lose the money.
Do not take a cheque, for obvious reasons!
Do not let them take the caravan until the money shows in your account. My bank say this could be up to two hours after it is sent, which I have always been prepared to wait, but it has actually always happened pretty instantly.
The note of sale gives both parties some hope of proving the sale of the other party plays silly buggers. For example CRIS won’t change the name on the registration unless the previous owners agrees it, but might with a clear sale note signed by the old owner.
It is nerve racking because it is a lot of money! Good luck!