My BP is 2', don't know his weight, and he's in a 30g tank. I used 2.5% limo black tint meant for cars on 3 sides of the aquarium. He has his two hides, his water dish, and some pieces of red slate rock to fill in space in the tank. There is also a piece of driftwood in there that he likes to climb on at night when he actually bothers to roam around. There is not a lot of crawl space the way I have it set up.

Just try to crowd the space up a little, get your temps/humidity right, do the foil treatment on the lid, and your snake should be fine.