I feed a couple of mine including the BP outside the enclosure in a tupperware feeding tub. You can immediately see her attitude change into hunting mode the second she goes in that tub. I usually leave her in there for a bit to calm down after eating, then gently move her back to her home.
She's generally pretty chill though. Feeding outside the enclosure might be more stress than it's worth for a snake that really doesn't like handling.
What about the substrate? Didn't want situation where it got caught in his throat. I'm using cypress mulch.