Digital BW, The Print

I know the issue of signing prints has come up before, and I've searched the
archives, but I can't find any solutions to my specific problem.

What do you use to sign coated paper?  Specifically, Epson Textured
Fine-Art, but I've noticed problems writing on EAM/EEM also.

I've tried fine-tip india ink pens and they always get clogged from the
coating after a few strokes.

Charcoal and carbon pencils either just scratch the paper (too hard) or look
like crayon on the textured surface (too soft).  Maybe I just haven't found
the right hardness yet, but I'd really like to sign in ink.

The only two pens I've found so far that work are:
  1. Cheap plastic ballpoint "syringe" pen (ebay item #1793004549) --
probably not very archival!
  2. Faber Castell PITT artist pen (brush tip.  other tips get clogged)  --
indian ink, but I'd like finer lines.

Any suggestions?

Thanks
--Tom