According to John Chilton in *Ride, Red, Ride: The Life of Henry "Red" Allen,* p. 33, Allen (who had played on riverboats in the 1920's) once explained that the riverboat scene was actually quite different from its popular romanticized image. No doubt his words will disappoint some people:
"A lot of people think, when you mention riverboats, you had to check your pistols when you came on, and that the boats were full of women good-timing, but I didn't find it like this. I do know that everyone had a good time but it wasn't as wild as some writers say, and I can't remember personally ever seeing any gambling on board when I was playing. This was Prohibition, so there were soda fountains for the people. Just in case things got out of hand there was usually a bouncer close by." https://books.google.com/books?id=gogjg5KvUxYC&pg=PA33
No pistols? No good-timing women? No gambling? Soda fountains? Truly, Mr. and Mrs. Beiderbecke had little reason to fear the moral corruption of Bix--at least from that quarter...
There's a reference to riverboat dixieland musician employment on page 102 of the Clyde Bernhardt bio, so short and direct that it left me wondering to whom it might refer. The description comes from 1931.
"It was that western weather that finally caused me to quit Oliver. Hot in the summer and so very cold in the winter. In October, when pop told me he was extending the tour through the year, I wanted no part of it. I gave him my two-weeks' notice.
'Now, don't be so damned sure,' he said, looking very serious. 'Back when I played the riverboats, if a good musician wanted to quit, he god-damn have to slip off the job.'
I asked why.
'Cause the old boat captain liable to frame you, say you stole some-thin', then make you sign a paper to keep working. If not, he put you in jail.'
I looked at him.
'But I don't think I do that to you,' he laughed."