The way i see it. if this is the girl of your dreams and someone you hope will be your last partner, and you really just want that closeness with her, than maybe it is worth some risk.
However, I'll bet this isn't really much to do with her. I suspect it's all about the ass, and she just happens to have one that's available. IMO, that's not a good enough reason to take that risk.
You haven't said anything about her previous experience with this. If she is new to anal, covered will be easier because some condoms fit tight, compact the penis a little and glide smoother through the lube. Plus she will be more relaxed not having lingering concerns about safety.
And she should be having lingering concerns. If she is so lacking in judgement as to jump right into BB anal, she's probably not a safe enough person to do it with.