Good for you lefty! I'm in that same lefty boat and I have customized all my basses my way. Parts, paint ect. I'm actually sanding a body as well. I don't do the filler, I sand and primer then sand it before moving on. The one I'm doing sucks as I have to take it down to wood whereas I usually rough up the old finish only. The paint in this was enamel and I'm using lacquer so it has to all be gone