I recently acquired an AP T8, as it seemed to be the most reasonably priced size, though I plan on only having one ball python.

The BP's I've been looking at seem to be around 8-9 months old.

I've read that BP's tend to do well in smaller spaces.
Is it really necessary to put a divider in? Or could I just fill the space with a few more hides or other cage junk to make it feel smaller?

One reason I'd prefer to use the whole cage is the mounting of the thermostat inside the cage, which I planned on screwing to the back, and drilling a hole for the probe to exit, and bring it around the back to another hole where the flexiwatt is. Just would hate to have to keep making holes in the cage as the snake gets bigger.

Also, I think half an empty tank would look quite silly.

I'm sure the true answer is to divide the cage in half and get two BP's.
Though that is not in the cards at this time.