I wouldn't use the stacking drawrs, the walls are usually very thin and can be pushed out by an eager snake. I would just get a regular Rubbermaid/sterlalite tub and some binder clips. Much more secure. Also, if you go to stack them with snakes in multiple tubs, you're going to have escapees. The tub "lid" for one tub is the bottom of another, so when you slide out one drawer you are effectively opening two.
And you will want to use aluminum or foil tape to attach the heat pad. Duct tape will get sticky and fall off. The aluminum tape is safe to use for heating elements.
There really is no need for a separate feeding box. If you feed in the enclosure put down a paper towel or something so he doesn't grab aspen at the same time as the rodent.
Other than that you need a water bowl.
Lookin good.