I have already cut the back portion out of the "toilet seat" and got it to fit with the angle on the back pack. Im insecure right now at how this angle will fit due to not knowing exactly where to trim the bottom edges of the toilet seat part.
Heres some pics to maybe help explain my situation.
Looking at other backpack/toilet seats it appears some cut the lines to match the red lines I have drawn onto the picture. Ive noticed other kits and originals tend to have a slight curve on the toilet seat part as to rest on ones shoulders.
The area outlined in white looks to be the part I need to cut out, but my question is how much? Should I take that part out all the way to the backpacks red line and then fill in the corners (green triangle piece) or leave some part of that area and fill in the corners (green triangle piece)?

Or leave as it and trim either the yellow or blue lines like below?

Id love to get the cut right the first time because I cant re-attach what I cut off.
