I am looking to fit a removable windshield to my 900 Classic to help whilst highway cruising but am not sure what size I should go for. I am 6'4" and have fitted a Saddlemen Solo seat which sits me about 1/2 inch lower. I have read on various posts that it's best to look over the windshield not through it and that Memphis Shades seem to do the removable thing pretty well. The question is, what size??? 21", 19" etc