That is a good point about the copper stitches. We had trouble with breakage too, and wound up drilling more holes and putting in more stitches in the “high-tension” areas. Your solution is more elegant and less sloppy!
If I had to do it again, I would use a heavier-gauge copper wire in those areas, maybe #14 or #16. I’d stay with copper because it should sand smooth easier than steel, which is probably the reason that these kits are supplied with copper wire.