That sounds like the right size to me, if the "ground boa" is full size. There is a few different types. Are you sure you're getting a dumeril's? If so, you need stuff for them to burrow into. I use newspaper and crumple it up really good for them. Also, I treat my dumerils just like any other RTB and they are just fine. The only thing they seem to differ from is when they are in shed. They only soak when they are in shed if I don't raise the humidity up to like 70%. That's the only difference that I've noticed.