How many heat sources?

[Homebody]

Would I need 2 heat sources in this size viv? And would I need some sort of heat source on the cold side of the tank to maintain ambient temps??

No one can tell you for sure. You need to set it up, test it, and make adjustments. Fortunately, you have enough time to do that. RHPs are highly recommended because they provide heat without lowering humidity. Ball pythons like it hot and humid, so I suggest you use an RHP. If you think a CHE would be cheaper, keep in mind that they are essentially light bulbs and they need to be replaced. RHPs last for years. In the long run, they are the cheapest option as well.

Will you need another heat source? I imagine that you will, but I would set up and test the RHP first.