Ooops, I should have clarified that---a clear-coat on top of decals must be done with a clear-coat that is intended for plastics. I have used a regular automotive clear-coat and it didn't stick. In fact, it peeled off almost immediately but thankfully, the decals were unharmed. I think that this may be dependent on which brand of powder-coat is used, but I am not 100% sure.

I've also been told that powder-coat is slightly porous and that water can get in under the coating. I don't really believe that but it probably wouldn't hurt.

Lastly, if you have to remove a powder-coat, use an automotive gasket remover.