Lucas Books should make a story set soon after Star Wars: Revenge of the Sith
where Threepio and Artoo make a pact using rapid, hyper(or sub)sonic conversation upon hearing that Threepio is to get his memory wiped. Just prior to his wipe, Threepio will transmit his memory to Artoo (Artoo had enough storage space for the Death Star plans) wirelessly. Then afterwards, and when it is safe, Artoo will re-transmit Threepio's memory back to him.
As a condition, Threepio will have to pretend that he has lost his memory and that his first occupation was loading binary lifters(?).
If you consider it, Threepio getting his memory wiped is akin to Alzheimer's in a human. Also, since Threepio was apparently given to Padme, in accordance with Naboo law, which gives high-level droids the status of sentient, Threepio would have been free, and wouldn't have been 'inherited' by Bail Organa--he would be protected by the Republic Constitution's [em]Right to Sentience[/em]. Thus, Organa wouldn't have the right to wipe the memory of a free sentient--Threepio.
Just some figurative two cents.