I've raised both meat and angora rabbits and I think the information I found about the mites issue was that you can use a flea powder that is deemed Kitten-Safe on your rabbits, but not just prior to butchering. Cannot remember the exact citation, but I have "Rabbit Production" as a reference, so it might be in there.
I know it's not a "natural" remedy, but it depends on how bad your infestation is.