I'm a lot shorter than you at 5" 7", but what I have in common is that my legs are short relative to my height and my upper body is longer. This results in the frame with the correct reach for me being one that is in my crotch if I am standing over the top tube. I believe Doesn't present any problem to me. Shouldn't be as much of an issue on a sloping tube design. What matters is the riding position being right for you.
I just measured the frame on my road bike and the seat tube measures just about 20" from center of the bottom bracket to middle of the top tube. That comes to about 51cm. It's a fairly short frame, as you can see:
So, for a guy 4 inches taller than myself, they are recommending a bike only about 1.2 inches taller. Perhaps I'm riding the wrong size, but all my bikes have been about this size and it certainly feels right to me.