Plumbing advice required.

[B4 Sloth]

Prior to building the Losi 22 that sits a few feet away I have to redo the bathroom

After spending a whole day faffing about with plumbing the bath in, with isolating valves that failed I do not want another torrid time of it tomorrow.

I have bought modular units. The soil stack is at 90 degrees to the pan. A normal 90 degree pan connector does sit far enough back to make 90 degrees and catches on the unit. I saw the flexible pan connectors, do these bend through to 90 degrees?
If not i feel its out with solvent weld and make my own up.
Sorry if it sounds like I am talking crap

thanks all