Hamelman light rye without yeast?

I am planning on baking a loaf of Hamelman's Light Rye tonight, but I'm considering making it without commercial yeast. I was wondering if anyone has experience doing this with this specific recipe.

For doughs developed using the Detmolder method, Hamelman says that commercial yeast is unnecessary, provided the baker builds in some extra time for proofing. However, he does not give a specific time. Besides, I'm not sure that this applies to doughs made using the simpler method outlined in the Light Rye recipe.

Could one forego the use of commercial yeast in the light rye recipe, and if so, how much additional time should be expected for each stage of fermentation?

The Light Rye formula is:

• High Gluten Flour: 85%
• Medium Rye: 15%
• Water: 66%
• Salt: 2%
• Yeast: 1.5%

In the final dough, sourdough makes up 16% of the total weight. Hamelman calls for 1 hour of bulk fermentation and 1 hour of proofing.

Thanks for your suggestions!

Eric