Can't help you with the Kodak source, although it shouldn't be too hard with some research to find the supplier to Kodak. There's only so many paper suppliers in the US. Good luck buying anything less than a monster master roll of paper, though.

Have you tried printing on the back of some FB papers? I have seen a print or two that looked good on the back side. This would only require that you fix out the paper and wash it really well first, but you probably wouldn't need to do too much other surface preparation. Some papers are printed with a logo on the back, but some aren't, so there may be a few options out there in this respect.

The Bergger paper is COT-320, which is made by Arches, and is a modification of the Platine paper. It isn't identical, but it it is very similar. I use that as my primary printing paper for normal pt/pd prints. It seems to have a little higher contrast and dmax than Platine, and it seems that it may also have fewer defects.

I believe the COT-320 paper is used by Bergger to make the Fine Art - Silver Supreme paper.