I keep my mainland whose still a little guy, only 3 or 4 feet long and still eating large adult mice in a 6ft by 3 foot by 2 foot tall. He does good, I have a hide for him on each side but he prefers to not use them and instead sit right up against the glass.
1.0 Normal BP
1.0 Mainland Reticulated
1.0 High lines Red Tail Boa