I'm ready to install the new 1-piece shower stall into the framed-in location in an existing bathroom. The ABS piping, including p-trap, is installed with the exception of the vertical pipe between the p-trap and the drain.
I'm having cart-before-the-horse confusion, at this step.
The drain is, basically, a 2-piece assembly, with the drain to be installed from the top side of the shower stall floor and a large washer and nut to go on from underneath the stall floor to hold the drain assembly in place.
Option #1: If I attach the drain assembly to the shower stall prior to putting the stall in place, this means that the ABS drain pipe needs to be installed prior to this, and aligned perfectly. In my mind I see a vertical pipe coming up from the p-Trap onto which I'll have to precisely aim the drain hole, while manhandling the very cumbersome shower stall, all the while trying to mate the pipe and drain and not snap off the pipe or mangle the seal on the inside of the drain assembly.
Option #2: I could place the drain's washer and nut underneath before installing the shower stall. Then after the stall is in place, I could install the drain assembly from above and try to attach the washer and nut from below. This is not an optimal scenario due to the limited access to the nut (basically, just fingertip room in there).
Option #3: Install complete drain assembly onto the shower stall floor. Cut to length the ABS drain pipe between the drain and the p-trap. Install the shower stall with drain in place, and with the ABS pipe loosely attached to the bottom of the drain (it's a rubber seal connection, not a glue-type). Then, from below, glue the pipe into the p-trap. There's limited room for this, but slightly better access than there is to the nut (option #2, above).
Which way would you attach the drain? Other ideas?