I don't think it'll fit "vertically", if that makes sense.can you fit your B35 in your keepall 55. I always carry my B35 during travel, it sits on top of my carry on roller...easy peasy.if you have a hardcover luggage (ie. rimowa) would be hard to crush. just make sure you stuff clothes or whatever inside the B35 before you put it in the dustbag so it doesnt fold over.
And also don't think it'll fit "horizontally" because it's too wide. sigh....