Regarding the mismatched hides, they don't need to be identical sized. Stuffing the larger one with paper towels is fine. I've done almost the same thing when I had hides that were too big...fill the bigger one with stuff to make it smaller inside. He's not measuring the hides to see if they're the same size.
Heat gradient is relatively easy. Put the hot spot and/or heat lamp at one end of the enclosure. The further away he gets from the hot spot, the cooler it will get.
Relax a little. He'll be fine. They're tough. They can survive long periods in bad conditions (witness a typical pet store snake that lingers in too hot, too dry, underfed conditions for months). Your's will hang in while you get things fixed and when you have it all sorted out, he'll pick up quickly.
Thank you very much. It's reassuring to know that he'll be okay, I just love him a lot and I'm one of those that tend to worry. Thanks again.