I'm in Vancouver. I used a piece of cardbooard approx 17" high and had someone hold it about 1" above top of headlamp and at same angle as forks. I used a steel measuring tape (as a straight edge) and ran it from the top of cardboard to the tip of my nose (as per one of the clearview methods). Based on these measurements, I think the 18" screen would work best for me.
Which dealer do you deal with??