How big are your boas? I was afraid that I'd have problems with caging and handling if they hit ten feet, so I stayed away from boas. My biggest are ball pythons. I also have a CalKing. I'm getting some thayeri kings. They will be small, but they are pretty animals.
I'm not sure how big the old girl is. I believe she was 11 or 12 feet the last time we were able to stretch her out. She's become a two person snake simply because of her weight and strength. But she's not aggressive; most boas are pretty laid back.