Yeah, I might go with tinting + snapping - especially now that I understand better how to do quantization/snapping after implementing dithcam. This will drastically reduce the number of sprites, as well as giving far more options to the person making their characters. I will have to test how the snapping will behave, might even use that for skin recolouring. Nonetheless, I digress!
Yup, you are correct, just add the new sprite sheet. Remember to create a copy of said sheet for every body/shape, as well as for the facesets. The naming should be the same across all folders.