Yeah, so the temperature you're interested in is the temp under the hide, right where the ball python's belly is. It's nice if the air temp (what the cheap thermometer actually measures) is at least 75F or better yet 80F in there (even on the "cold" side). But it's the warm spot that really counts.
Ball pythons like to be warm, but they don't really use "basking" spots the way lizards or tortoises do. What they like is a choice of hides--one on the warm side AND one on the cool side. That way if they need to cool down, there's another nice secure hole they can tuck into and still feel safe.