When using send skin does your consciousness have to be in the skin to control it?
It must be. The spell says that while your consciousness is in your body you are helpless except for " transferring your will to your skin, or dismissing the spell".
Helpless says the following "A helpless character is paralyzed, held, bound, sleeping, unconscious, or otherwise completely at an opponent's mercy."
While it doesn't explicitly say "your consciousness must be with your skin to control it" the fact that it says you are helpless except for being able to do a small list of things leads to the conclusion that if whatever you want to do isn't on that list, you can't do said thing.