55 gallon tanks are tough because they're sooooo tall and it's hard for over head heat to get down to the ground where the ball pythons are. Also, as pointed out, the thick glass on the bottom of the tank makes a UTH less effective.

I have a couple thoughts, but I'm not sure how good they are .... Bigger and several UTH's coupled with some over head lighting/CHE's until you find the correct mixture might work ... experiment with different combinations until your temps are correct .... you'll have to keep a good eye on humidity because all of those heating elements will fry the air, but it can be done.

If you're thinking about putting a custom cover on the tank (like plexiglass) you could always invest in a radiant heat panel and attach it to the plexi. I am not sure if this will work, but those heat panels are great at throwing a nice even heat down without drying things out. If you'd like more info, let me know.

Supplimenting the room heat at night with an oil filled heater will work too. You could probably run it on low from 8pm-8am or something like that without using too much electricity.

There is another thread about wrapping an aquarium in insulation. I've never tried it, but it might be a cheaper option to explore if your on a budget (I know how moving can empty a wallet quick). A nice piece of pink board under the tank might help a lot (making sure not to compress the UTH's of course).

If I think of anything else, I'll post it.

Hope these help get you started.

-adam