I'm using a 121 Qt clear tote for a humidity chamber, it's 17 inches high, I had to go to that size to have room for any upward growth. Now, I'm thinking about turning one tote upside down over the other. That would give a chamber almost 3 foot high, cheap, and you could get a plant up to a descent size in it, especially if you prune to force density. You're growing trees like blowing up balloons. pity not to have room to take them up to production size.