Great advice so far!
Don't worry about the moss. Gio put it great - damp vs wet are two very different things. Don't worry about tweaking the enclosure as you go along - if you are doing your best to not disturb him, a little tweaking is fine. Boas don't stress as easily as balls so you shouldn't have to worry too much about bothering him.
I'll also echo Gio's recommendation that you ditch the tank and get a pvc or plastic enclosure like he pictured. You won't have to tweak nearly so much.
Enjoy your baby!!![]()