When I played Piccolo bass way back when, I used a 1966 Gibson EB2D bass, with the Push switch engaged.
it gave the most amazing Les Paul type sound, and would even produce that old octave feedback sound that old Juniors gave.
I loved it..........my strings were.....
20,32,50,62.....all guitar strings!
It was great until I loaned it to my friend in London, and he snapped the head of it......twice!!! Arghhhhh.
I traded it after that.....wish I still had it though!
George