I use mostly CB70 tubs which are almost the same floor dimensoins only the height is the big difference. So it's really a normal size adult tub that is taller. As a matter of fact my freedom breeder rack has the CB-70-8 tubs which are 8" tall instead of 6" and thats what I keep my breeding females in.
Any way your tubs aren't really that much bigger because floor space is what makes the greatest difference.
I myself take my snakes out of 32qt tubs when they are 700-800 grams unless one happens to be a real nervous nanny.