I took a crack at it… i think its close to what you’re wanting.
Here are the pattern positions i ended up having to use….
Red: Used to crop out old color
Yellow: used in conjuncture with another collar.
Green: Same as yellow with yet another collar.
Cyan: Used in conjuncture with another undershirt.
With a couple more mask, and careful tweaking it may be possible to completely fade out where the old collar starts to begin. That just requires way more patients than i have at the moment. Good luck, mate!
