One hide or two? As far as this screening are you talking about on the lid of this enclosure? If he doesn't climb how is he reaching up to rub or what exactly does he do in order to rub his back raw like that? Are you sure it's a rub and not a burn from exposure to an overhead heat source like that lamp you mentioned? What do you use to measure temps and humidity in his enclosure? After a regurge you need to be careful and follow a special feeding protocol or you're likely to just cause another regurge and get into a really bad cycle that way.