I've got my boa in a T13 with a shelf. It's a great enclosure with a decent bit of space. They're on sale right now, as well. Then again, so is the T10. I think the extra height and width is worth the money, because it also allows to add bars, or other platforms which increases surface area within the enclosure. But it's entirely up to you. Your boy is on the smaller end of the scale, so you may or may not need to upgrade in the future.

As for heating, I have 9 PVC enclosures, most of them from AP, and I have proheat radiant heat panels in every one of them. They are the best heat source I've found, and I can't say enough good things about them.

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