Charles, I’ve also heard of using liquid coffee and/or instant coffee in pumpernickel. Your modifications such as cocoa powder also sound familiar.
Advice on stickiness for this thread in general:
During the bench rest, I left the dough uncovered, which allowed the top of the dough dry a bit. During shaping, I made sure that “skin” was at the top of the long batard–which then was flipped into the proofing basket (dry side down). The underside of the dough was still very sticky.
I didn’t flour my proofing basket more than usual and had no problem with stickness - following the recipe to a T except that my whole grain rye flour was sprouted.
Here are some pictures. I baked it in an oblong clay baker. Got way more oven spring than I expected, but I don’t look a gift horse in the mouth even if it tears through my scoring 
