Its the same with my Dumeril. She weights 15lbs and its not cake walking around with her. She's about the same size as a lot of RTBs (6.5 feet) and when they hold on its tight- when they startle its really tight. The Dum isn't as active as the RTBs but its still a chore. We interact by sitting in a recliner at night. I watch a move and she leaches my body heat.
The RTBs I had were BCC. We're talking 11 and 9 feet (and still growing). Thats a lot of snake. Even at 8 feet they can be a bit much to handle. They don't recommend people handling 8 feet and up snakes on your own (especially for new owners) They are very busy and not really just content to chill like my Dum or BPs.
TRBs are stunningly beautiful and easy to care for. They are veracious feeders. When my boas (even the Dum) smells food they nail anything that moves.
I love boas and BPs. I would strongly suggest that she interacts with both heavily BEFORE she decides on a snake.
Would she be willing to learn about other boas? There are amazing ones out there! Like the Dum...(I really am a sucker for these guys).
It also helps to know the state, county, and city laws where you are too. Most cities don't allow snakes over 7 feet. Food for though.