By his own admission one senile fool keeps losing his key, can't work out how to secure his bike while he lugs his (and his wife's) prodigious quantity of luggage into a hotel room and is astounded by BMW's reluctance to drop their kecks to assist him.
Easy solutions:
1. You do get a spare plastic key, which will run the bike. That is your most pressing problem over and will mean that you won't get stranded.
2. If your only remaining concern is your inability to share one key with your wife on the occasional luggage ferrying duties, but you only need the second key to open / lock the panniers; get a second non-transponder key cut for a couple of quid.
3. Still worried? Easy. Glue or tie or somehow secure the spare plastic transponder key to the metal blank. Bingo, one for fully functional spare metal transponder key.
4. Still stuffed? Buy a 1600 where the panniers are all locked centrally, meaning you don't need to touch your transponder key from the moment you leave home to the moment you come back. Secure it into your jacket or shove it somewhere really safe and don't touch it.
5. Still no good? Work out that the bike and the 21st century really do not suit you.