You can absolutely drop below 50%! My normal humidity is around 40%, bumped up to 60-70 during shed. Nothing bad will happen if your humidity dips too low. Maybe some dented eye caps, but that is an easy fix. I think having humidity above 60% constantly is just going to make a great breeding ground for bacteria.
My suggestion to you is to create a humidity cycle, as would occur in nature. It rains, it gets humid, the water dries up, and so does the air. I do this for all my arboreal animals. I spray once in the morning (enough to fog the glass) and once in the evening if the humidity drops below 30%. The tank needs time to dry out or you will get all sorts of gross bacteria and mold growing.
OR you can create a humid hide and then you don't need the fogger at all.
You are correct, there is no exact science to keeping ball pythons. Everyone does things a little differently. In my opinion, high humidity like that is just more likely to cause problems than it is likely to solve problems. Boost your humidity to 70% during shed and thats it!