Can it be done? How? After Effects? If so, is there a specific tool to use, or just “masking”? (I don’t have After Effects, yet. If there is an alternative, I’m interested.) I have Vegas Pro 18 – no other video editing software.
Depending on what else is in your shot, I’d recommend one technique or another.
First thing I’d ask is “is there anything else in the shot that tightly matches the skin color, that you would object to changing color of?” If not, look at the Secondary Color Corrector. It lets you identify a color by hue, luminosity and saturation (you can just click a spot on the skin as a starting point), and then adjust aspects of that color to make it something else. This might get you where you want to be.
If that doesn’t work, consider motion tracking (frame tracking) and if you can build a motion mask then you can tweak the properties of the mask without having to manually track frame-by-frame. For this you can try using Vegas’s Bezier tracking or a 3rd party product like Boris Continuum which has Mocha tracking.