I think you're right when you say the most important thing is a high temperature basking spot. 65+ sounds perfect. I've never had any skin constriction problems with my monitors, so can't really say from personal experience what causes it. You see heaps of monitors (and dragons and skinks) in peoples' collections with missing digits and tails, I'm not sure, but my guess is that the typical causes are different between the lizard families.
By the way, did you buy your gilleni from a guy in Melbourne?
