No objections to any of that, other than that if the tree grows very fast and the homeowner forgets about it, it may cause more trouble than my way. When it reaches the first nut, the bark has already engulfed the hex part of the bolt. So the bolt cannot be backed out, and the light would need to be rehung on new bolts. Depending on the tree, this could happen many decades later, or just a few years later.
Una