I purchased a 16ml clear from an online pool store and their in-ground aluminum signature series reel. I set it up with the reel at the very end initially but changed it after a year to the reel crossing about 3' feet in at the top or the widest part of the bean. I think I was concerned about the cover rubbing against the concrete coping when I rolled it up/out. I didn't really like the look of the reel across the pool even though it was easier to roll.
My lessons - the cover bubbles started wearing off anyway at 2 years but not just where it rubbed initially, the bolts in the reel wore at the cover where they screwed in to hold the aluminum reel sections together, my robot cleaner ripped away at a small cut out section on the side and the straps from cover to reel were deteriorating and 1 tore. I did keep a white tarp cover over the solar cover when it was reeled in.
It really helped raise the water temp, maintain it overnight, reduced my use of chlorine and extended my swim season longer than my neighbors. I plan to purchase another cover but somehow rubber coat the reel bolts to not wear, probably keep the reel at the end instead of across the pool and plan to replace the straps and cover every 2 years.