I just moved over the weekend, and my dad took down his 180gal fish tank, kept the tank and stand, and blah blah. I've been looking at it ALOT and been thinking of how I could cover everything and make it hard for my boa to escape from. I'd say, just try to find something bigger and get creative, sit there and stare at it and think of how to make it work out LOL. I need to spend more time working on my dad so he'll let me convert it, and less time planning out the conversions. But, I think your 40gal is only two and a half feet in length, and that's too short right now. Maybs buy another 40 and try to figure out how to combine them