I put in a lot of showers with no doors. When the shower is on it creates a higher pressure in the shower which actually forces the air out of the shower so you really do not have a draft entering the shower.

Brrrrrrrrrrr. I had one and never would again. I would have put a door on it but it was too much of a weird angle opening to bother with so I just put a portable heater by the entry. Your backside or front side will get cold if it isn't under the warm water. If you like a warm shower environment during and after the shower, this is not the best way to go IMO. I'm cold by nature and that may be a factor that you need to take into consideration, too. And I thought my water pressure was fine..

Why not just do glassw alls with the opening at one end