Since you're using a glass tank, why not put up some nice scenery around the sides & back, then insulate with the material of your choice? (insulate using foam-
board, cork tiles/cork roll, etc etc.) Privacy can be more practical & attractive than just blacking it out. I'm so not a fan of spray paint, & IF you use it, be sure
to get no-VOC type paint...all odors must be gone around snakes, most paint & stains take time to cure & give off toxic fumes.