I stretch mine out streamside, but I think if I were doing it like you are, I'd take a Sharpie and mark them before I hung them up the first time. Do it kind of like a Roman numeral system - use a narrow line to denote one and a thick line to denote five. Starting from the loop end and marking it close to the loop, a narrow line followed by a thick line denotes a 4 weight, a thick line followed by two thin ones indicates a 7 weight, etc.