Thanks, bfato.
Indeed I do mean a pleasure flight in a little piston engined two-seater.
A Cessna 152 to be precise.
Yes, the cockpit is quite noisy but I have a noise cancelling headset that my wife can briefly swap from the one she will otherwise wear in the aircraft. She can also squawk me (no speech) in such a way that I will know it is her, not anyone else on the same frequency. It's just the legalities I was concerned about, and from your reply I don't need to worry other than the courtesy of a quick chat with the pilot beforehand.
Cheers.