I have a bathroom with a very low ceiling of 81". The height of my tub is 13" and from the top of the tub to the ceiling is 68". I'm looking to buy a semi-frameless glass bypass door that is tall enough that a 6' person won't have to play limbo to get into the shower, but also low enough to allow an adequate ventilation gap at the top.

Seems like the Lowes/Home Depot standard is around 58", but that seems short. I've seen a 62" tall door, but would a 6" gap at the top be enough for ventilation???