I currently have 5 snakes. I am adding 4 more in the next couple of weeks. Now, I have all mine in seperate tanks, but, I am looking at investing in a setup identical to what you have. I only have one Red Tail but I do plan on adding a Brazillian Rainbow to my collection in the coming months.
As Lace said, don't worry about what other people say. If you are cramped for space to begin with, then a tub system only makes sense. We converted a bedroom and even had to take a wall out and convert a 1/2 bath to make more room for our pets. You do what you have to in order to make things work, and that's exactly what you're doing. I don't see where your snakes are being hurt or neglected by housing them the way you are, so by all means, carry on! Personally, I think your setup looks great!!!