If I'm going to be playing where there is a low ceiling AND the band isn't "strolling", I'll use the big Martin with a recording bell. In my opinion, this horn is the thing for "tuba as bass" situations. Also great in the open air if the band stays put.
If the band will "stroll" I'll tend to use a top action 3 -valve Martin with an upright bell using a stool. "Strolling" is not "marching", (playing and moving at the same time); "strolling" means the band walks to different locations on the gig. I say this lest you picture me doing something akin to Woody Allen in "Take The Money And Run".
A cheap (lightweight) bar stool works if you cut the legs down so that you can sit at a comfortable height. The older top-action Martins have an upper branch that you can get a good grip on. I use one that has seen it's share of dents since this environment has its risks and the top action avoids the risk of shearing off valve buttons/stems while maneuvering through crowds/chairs/tables. I avoid the big recording bell whenever I have to maneuver through crowds, especially when "playing tables" at country clubs. It's quite easy to bash into patrons, waiters, etc with a 24" recording bell!
I have developed my own strategies to avoid whacking folks with the stool (the things they don't cover in college.....). The stool can also serve as a makeshift table to put a plate on during a break, (most places will let you eat but want you to do it away from the patrons).
I recall doing a job that had a marvelous buffet, the kind with all sorts of hot food under those lidded trays. The country club was confident that the musicians would not eat since utensils were not made available. One intrepid musician simply dug in with his hands. We were never asked back of course, but it was worth it to see!