Thanks for pictures of how your dough balls looks at around 60 hrs. To me the dough did look ready to used at 60 hrs. I really donít use a lot of rye flours or wheat germs in my doughs, but found when using whole wheat flours in dough there were more problems with oven spring and a denser crust. Do you know what the combined protein there is in the rye flour you are using and also the wheat germ. I would think that with these protein percents combined, those could be affecting gluten development if the proper mixing times arenít appropriate. Gluten chains are important, but if the gluten bonds get too strong, I would think that also could make a more dense crust with less oven spring. Maybe the preferment with the rye flour in combination with the added wheat germ and rye flour are affecting your extensibility. Maybe you even may need to try a lower amount of preferment in your dough.
I am not a dough expert, so I will wait to see what Peter has to say. He knows a lot more about flour and how protein content can affect doughs.