It took some practice, but I have learned to pee quite well in a wide mouth nalgene. I have also used a heavy duty, freezer zip lock bag. Opens wide and is quite lightweight. But that was just a one time thing.
But I would probably use it again in a pinch. I have thought about buying a wide mouth tupperware container just specifically peeing. But to get good at this stuff, ya just gotta practice. Haven't tried the lady j and I'm not interested in drinking my own piss.
Now, pour me another Black Butte Porter!