Carsten, how much of your frustration is due to your desire for background isolation? Because, in my experience, Zeiss bokeh is much more "structured" than that of other lens brands. The classic example is the Sigma 50mm f:1.4. Whereas, with the Zeiss the background will still be recognizable, though totally OOF, with the Sigma is is not only OOF, but also de-structured (or blurred if you prefer).
In this respect, and while I value my 50 f:1.4 greatly, I am not sure that it would give you greater isloation than the 50MP. If that is the case, the obvious (and painful answer to your prayers is not the 35 f:2.0, but the 35 f:1.4, with its gorgeous, liquid bokeh. Ouch!