I think carefully vetting the buyer, to make sure he/she is COMPETENT and not braindead, would go further to protect you as a seller than anything else.
What a lot of people don't think about is that in the case of a casualty, you will more than likely be dealing with the family of the buyer.
When I sell an amateur-built aircraft, I have the purchaser's next of kin sign the disclaimer as witness. Nothing is guaranteed, but this at least shows that the next of kin understands to situation.