I personally believe that a 2ft height is ideal, especially for males and many keepers have noticed that male bps enjoy climbing more than females (on another note, I have heard and experienced this same before with other reptiles and amphibians. Perhaps its a form of male-exclusive risk taking for food or mating opportunities commonly seen in some other species? Not sure, its just a theory). Anything above 2ft would likely be a fall hazard however. I personally plan on getting my male bp a 48x24x24 once I get back to working. At the very least, I think 18in is the minimum for males and 12in is the minimum for females, although I think 12in is still kind of short.
Enclosure sizes can be difficult to figure out. Many people who keep rabbits as pets would disagree with me using a 36x30 wire bottom cage for my show bun, but I understand where they're coming from and I try to respect that. Luckily, this forum isn't as chaotic or judgemental as the reptile subreddits that a lot of these new care requirements come from so healthy debates can take place here and education is placed above personal attacks.