Other than beating the coating off chopping through rough bark, using a highly abrasive sanding material is about it. So either low speed (hand sanding) or high speed (air/mechanical powered) is pretty much it from what I have tried. Keep in mind that depending on how you do it, you may wind up removing a lot of CBT material as you can see starting to occur with the flatter sections in your pics.
The powdercoating is much easier to remove.