Would it not be a code violation to use a grounding bushing outside of an enclosure? After all, if the bushing is outside of an enclosure, than the ground wire has to be exposed and not protected. Or am I wrong yet again.
Equipment grounding conductors may be either inside or outside. The continuous connection is what is important. When outside it must be protected from physical damage. You can use a grounding lock ring inside a letter if you wish.
Neonsignfire