Rakshasanyc

Most herpers will tell you to steer clear of hot rocks; snakes and other reptiles frequently burn themselves severely on hot rocks. (They fall asleep on them and don't realize they're cooking themselves...). Instead try to get an under-tank heating pad: that will provide warmth without the danger of coming home to a sunburned (or sauteed) snake. Alternately, you can use heating lights: I'm sure there are a number of people on here who can give you some other ideas.

A 50 gal. tank should be more than enough for a ball python throughout its life, but a Burm will probably outgrow it within a couple of years (and maybe within a year, depending on how much you feed it). If you're handy with tools, you'll ultimately do better making a custom enclosure for a big Burm. (You won't need that at first, though: this is just planning for the future).

Also make sure to get a hide box or space where the snake can crawl into and be sheltered from prying eyes. If you don't have that, the snake will start getting stressed out and will either get nippy or go off its feed altogether. (The latter is more likely with a Ball; the former with a Burm).

Best of luck with whatever snake you get. I can't blame you for loving Burms, since they're my hands-down all-time favorite snake.