Billy the Bus,
I was graced with the opportunity to see Jesse just one time live. It was magic. Easy rider missed noting that he had a kazoo strapped next to the harmonica on his harp rack. Just another thang. I've usually seen his bass instrument listed as a Fot-della, but what do I know.
The foot pedals were just the same as you use for a bass drum. From the brief little bit I saw of it, it was a wooden chest and I saw no remnants of a double-bass. It was strung with piano wire as I recall (we are talking 1967 or so).
Roger in Baltimore