Hi, welcome to the Spine forum!
Unfortunately, it is not possible to set up like changing the skin changes the draw order, so the only way to do this is to prepare slots for the different draw order in advance and change the slots to be used for each skin. Sorry that I can’t explain this in words well, but I've prepared a video instead of that:
Look at the tree view in the video. This skeleton has two slots for each arm image: one slot above the head and one slot below the head. Then, depending on the skin, the arm image is set in the slot above the head or in the slot below the head.
I hope this will help you.
Re-reading this post again, my answer seems to be quite misplaced. I assume your question is that you want to change the draw order without separating meshes? The draw order is managed by slots, so you can't change it unless you separate the slots.
As a result, you still have to create slots in the order you want them to appear, as in the video I posted above, but I think the way I answered the question was wrong, so I added this.
