I find that it's clutter and hides moreso than size of the enclosure that determines how stressed a snake is.

lol, Guess my girl doesn't deserve to languish in her tub with all her plants and nice burrow-able bedding and hides. Better put her in a tank so I have a harder time keeping her humidity right.
If you didn't mean to imply that keeping BPs in tubs versus cages was cruel, you really ought to rephrase what you said. My snake has fift-five gallons of space to roam in and regularly uses about five of them. My guess is you're going to see the same thing once yours settles down.