Appreciate the suggestion for a second CHE. I don't have a UTH, only the CHE - with a wooden viv it was my understanding no heat would come through from below so I'd have to go with putting the mat inside, or inside under a false bottom. I wasn't too happy with that considering he's a big snake, and with no RHP sellers in the UK I went with a CHE.

And yup, he's an adult - 900g, and I believe he was in a 3 foot tank before.