lets put the keyhash in a low rate bitstream and add it into GPS and Glonas packets. If we write the code, then we can extract it at one bit per minute or something, and every phone in the western hemisphere with Android or iOS will have the pubkey.
anything else is just quiche.
or, we could ritually all incant the keyhash in plenary at the mike, for the next meeting. That leaves newbies exposed to a +1 risk unti they come to another IETF.