David gave some good advice. You just have to kind of play with the heat levels and the thermostat, and figure out what you can leave it on to keep proper temperatures.

About the rubbermaid lid, I use Bulldog Brand clips that you buy to hold papers together. You buy them at Staples or Office Max. (I think even Walmart or the 99 cent store has them, I wouldn't doubt it). They have worked great for me. And you can put a brick on top of the lid, I have one of those for extra security on my rattlesnakes cage. Or, you can buy a locking mechanism.

Everything else sounds great! So, where you going to buy your ball python from?