FWIW, I don't add sulfate to my maltier lagers and I've never missed it. I shoot for about 80ppm of chloride from CaCl or a mix of CaCl and NaCl and adjust pH with lactic and that's it. I try to K.I.S.S. with my water additions and don't add something unless I see a clear need.
As far as recipe goes, I equate Dunkel with the flavor of Dark Munich malt. I do about 85% Dark Munich and 15% Pils. The Pils is mainly to boost the enzymes so it doesn't end up overly chewy. Honestly, I'm not even sure if it's needed, but it makes me feel better. I've enjoyed both WY2633 and 34/70 as the yeast for this. If you have a cake laying around from your Octoberfest, this is a great style to repitch into.