Pumpernickel -- when is it done?

This may seem a silly time to ask, my loaf's in the oven as I  type, but how do you know when pumpernickel is done?

I'm baking a traditional Westphalian version, 100% rye (45% light, 45% medium, and 10% flakes) at approx 70% hydration. Temperature started at 350F and is being lowered 25F every two hours 'til it's at 225F.

Everything I've found for all rye pumpernickels only gives ranges somewhere in a 16 to 24 hour window.

I have a roaster pan with water on the bottom rack, and another roaster inverted over the Pullman pan to trap the moisture (not any sort of seal).

The aroma test seems a bit vague, as the kitchen end of the house has had an aroma of chocolate cake baking since about two hours into the bake; and no, there's nothing but rye, salt, water and yeast in the dough.

Any suggestions?

cheers,

gary