I overlap skins at glue up. Then before the glue is dry I use a razor to cut a straight line across the overlap. Remove the now loose top skin piece you cut off, lift up the top piece to be left on the bow and remove the cut peice from the bottom skin. lay the ends back together. This makes a pefect seem. Watch a wallpaper hanger,,, I do it just like that.
If you take time and have enough skin to match the pattern at the seem, you'll think and it will look like it is one skin.
When rushed for time, I'll sometimes use my 1" belt sander with real fine 400 grit paper to finish off and remove the excess skin at the profile lines or edges of the limbs.
Scales should be removed from skin before applying finish, I use shipping tape.