My understanding is that it is now possible to have multiple skins active on a skeleton animator. How exactly would one go about doing this and is there a way to do this within the unity editor?

Nevermind. I didn't do a thorough enough search. I set this up with multiple skins and found the useful page in the documentation.

Spine-Unity Mix and Match

Incidentally, I believe there is a typo in the skin related code on this page. It says:
myEquipsSkin.AddAttachment(goldArmorSkin);
myEquipsSkin.AddAttachment(redGlovesSkin);

and I believe it should say:
myEquipsSkin.AddAttachments(goldArmorSkin);
myEquipsSkin.AddAttachments(redGlovesSkin);

Thanks!