This uses a texture pack and is very simple. The only downside is when you are on a multiplayer server. It causes all steves to be your skin. To do it, rename your skin file to steve. Then go into your resource packs folder and create a file and name it whatever you want. Open the file and create a notepad text. Put this into it:
"description": "Skin Servers down? No Problem!"
After that create another file inside that folder that is called assets. Then put a folder inside the assets folder that is called minecraft, and inside that folder put a file named textures. Then finally put a file in there named entity. Put your skin file in there when it is renamed steve. If it does not work it is either because you put the folders in the wrong place, named them wrong, did not put the notepad in, or your skin is not named steve. If your skin is alex, do the same thing except name the skin file alex. This will ONLY replace your skin when the skin servers are down!
To activate the texture pack, go to Minecraft and go to the pause menu. When you are there, go to options, resource packs and then click the arrow.
A video on it: