Advice needed: Spiny-Tailed Monitor

I was just over at my friend's house and he was showing me around his gecko room so that I can watch over them while they're gone for an extended weekend. He showed me what he called a Spiny-Tailed Monitor that he got from the family of a friend who just passed away unexpectedly. Something makes me think the guy would be rolling over in his grave if he knew the poor thing was being kept in a shoebox-sized tub in amongst a bunch of leopard geckos. Apparently the thing is quite valuable, and it does appear to be in good health. I admit I don't know squat about monitors, but I KNOW that an un-lit shoebox on heat tape isn't going to cut if for long.

The animal is about 12-14" long, and amazingly easy to handle. I was thinking of bringing him home and putting him in an empty 29 or 45 gallon aquarium with a basking light and UV bulbs, but other than that I have no idea what type of substrate, humidity, basking temps, food etc. that this thing needs. I would take an aquarium over there for him, but they have absolutely NO room for even a 10 gallon.

Any advice would be greatly appreciated.
Thanks in advance.
Paul