Our stall shower started to leak to a lower floor where I could access the bottom of the pan through the ceiling. The shower base appears to be fiberglass. It has a PVC drain body with the drain pipe cemented in place. The plastic nut holding the drain body to the shower base was loose and the water was coming from between the drain body and the shower base. The drain was installed with nothing (like caulk) between the drain body and the shower base. So, I think I can fix this by putting silicone under the drain body and tightening the nut holding the drain body and its rubber washer against the shower base.

The problem is that the nut is in a tight space where I can only grasp it with my left hand. There is no way that a pipe wrench large enough to fit the nut could get into this space. Is there another tool that might work or should I try to find a strong left-handed friend?

Thanks