That's a good idea. I use to just put a small piece of leather under the clamps. Those hobby lobby clamps work great tho. There's like 30 or so clamps in a pack for I think $10. Not a bad deal.
Very nice! That's a lot of stitching. That's the only thing that keeps me from wanting to make a belt. I figure I would have to have at least 20' or more of thread to keep from tangling up while hand stitching.