Where do you live exactly? I ask because the places that I live have been hugely different in terms of how my snakes shed.
In Colroado Springs I completely mist everything in the tank about twice a day while they are blue and make sure to keep their water bowls filled so that they can soak if they decide that they want to. If I don't do this, for instance when they shed while I was down at Ft. Polk, Louisana for three weeks, they will not get a single piece of skin off on their own. When I got home I had to place them into wet pillowcases for an hour and then rub the shed off by hand to get them clean, which is stressful to the snakes and myself, as I worry about my little ones!
In Kansas, where my wife is now with the snakes while I am in Afghanistan, they need no misting at all to shed in one complete piece. They have water and may soak, but I can't be certain without asking my wife. As a side note, my male pastel that ate 4 times from October to March in Colorado has now eaten 4 times since 1 April! While I am super happy about this it is frustrating none the less. Who knows what his deal is!?
As for substrate, (not sure what you are using but someone above recommended cedar mulch) I wouldn't recommend cedar mulch. I have used it in the past and while it does hold water well it has some other aspects that can be causes for concern. First is that if it sits wet for extended periods of time it can end up growing mold and releasing spores into the air that can be unhealthy for not only your snake but also for you! Second is that I have talked to people, namely Greg Graziani of Graziani Reptiles, who have seen the companys that make the mulch at work with bad things to say. What Greg told me is that not only do the workers at the businesses relieve themselves into the mulch but the machinery that moves the mulch will have hydraulic lines break and will dump hundreds of gallons of hydraulic fluid into the mulch. While expensive, I use carefresh bedding and I LOVE the stuff. It is super absorbent and always make cleaning up "messes" nice and easy. In addition, if you don't want white or any of the colored bedding you can go with their latest release of their naturally colored bedding. It is brown and has bits of wood matter still in it so it looks completely natural.
It honestly sounds like you may be misting too much. Where is the hygrometer located? If it more than an inch off of the substrate it won't give you an accurate reading of where you snake is actually at within the tank. Ultimately, maintaining humidity is more of an art than a science. Remember that snakes have evolved the ability to shed their skins over millions of years and are actually quite good at it! As long as you are misting once a day and have water in a dish for your snake to soak in you should be just fine. Let us know how the shed ends up going.
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