Adult Male Bioactive Tank Size

I have a male ball python who is still a little boy (350g) but I want to prepare for the future. My goal is to get all of my reptiles in a bioactive environment. Typically it is said that a 40 gallon is minimum for an adult BP. I however want to make sure my tank will be able to be dense with plants for my BP to feel safe in. I have a 75 gallon that I'm saving for my bearded dragon once it grows up (still a baby right now). Do you guys think a 50 gallon or 55 gallon would be large enough for what I plan to do? Or will I have to get a second 75 gallon at some point?