In one of the posted comments it was interesting to see a mention of a ukulele. After an unhappy experience at check-in at Gatwick ,where I had to dismantle and pack a tenor banjo, I now travel with a tenor ukulele.
I always said it was a cryin' shame that one could not find a banjo rental anywhere. Every city of even modest size has orchestral rentals, violins, tubas, piccolos (piccoli?)...but no banjos.
I have a 'travel banjo' that works quite well...even though it doesn't really sound much like a banjo (it is basically a stick with 5-strings and an electric pickup). However, I stopped travelling for a living some years ago and it hasn't had much use in the last 10 yrs.
Sam Farris makes the "tranjo". I played one some years ago, it sounded quite good!