| I would take the cheapest heap of s**t that you can find that will get the job done, as it is quite likely to get totally f****d. But it depends what the gig is. When I was on ships for a few years, some gigs you would play in the same lounge night after night. Others, you would be on the deck in the sun, then an air conditioned room ,then an unaircontitioned bar full of people,then across to the other side of the ship (better run 'cos you've only got ten minutes between sets) to play back on deck in the cool night air. NOt every days schedule, but one day like that every week can seriously stress out any average piece of wood and glue. I only did that gig with a bass guitar, but the neck was moving so much that when I returned to the ship after a holiday ,I had a graphite neck fitted (to the bass, not me) which calmed the action down.
Check out graphite double basses. I haven't played one, but some people seem to like them, and they may save some hassle.
I have heard that plywood basses are good at taking knocks but are more prone to humidity changes? | 
