Fred, can you define "rustic bonsai"? Would you tend to think of it as the same as "naturalistic"?
To me, in the context of "arts and crafts" for instance, "rustic" means undisciplined...not polished, not finely crafted...like a sign made out of an old barn board, or a birdbath made from an old rusty bathtub. While there would be some charm in a small, slightly overgrown stump in a pot made from fence posts or whatnot, would it be bonsai?
Show us a picture of your most interesting "rustic" tree, and give us something to work from. Words aren't going to get us anywhere.
Joanie