The couple times I had bad sheds, I just put the snake in a tub of luke warm water just over half their body deep, put the lid on and let them sit in there for about 30 mins. Assuming you are in a fairly warm room, the water should stay fine. Then I just let them crawl through a wet washcloth or paper towel. Worked fine but then again I never had a snake that had 2 or more layer of stuck shed or was that badly dehydrated. Like BCR said, keep him in high humidity. I keep Caesar and my boas at about 80% humidity and they all shed fine.

Also that snake should easily take small rats. Caesar was taking small rats at about 2' long. He's about 5' now and taking medium rats which seem to last about 4 days before he starts pushing, digging and climbing all over his shelf and destroying his silk vine

That snake doesn't even have the raptor looking head yet, you sure its 1.5 years old. It has the same kind of rounded head Caesar had when he was 5-6 months old. Now he has the wide raptor adult looking head. He's even got the big baby eyes. Or he was really underfed

Anyways, let us know how it goes and good luck.