As I wrote here a couple of weeks ago (on a possible German victory in 1918):
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A likely option for a victorious Germany: supporting neither the Bolsheviks nor the pro-Allied majority of the Whites but setting up a puppet government of their own like Skoropadski's in Ukraine. Krasnov
https://en.wikipedia.org/wiki/Pyotr_Krasnov would be an obvious figurehead...
(In OTL, even when the Kaiser rejected the idea of military intervention against the Bolsheviks in the summer of 1918, he significantly added the words "without foreclosing future opportunities."
https://books.google.com/books?id=5mSkxsos488C&pg=PA184 A German victory in the West might provide such an opportunity, given that the Germans were well aware that the Bolsheviks still wanted a revolution in Germany.)
The Bolsheviks might be the lesser evil compared with strongly anti-German moderate socialists and Kadets (some Kadets, like Milyukov, were willing to reconsider their hostility to Germany, but they wanted a serious revision of Brest-Litovsk). But was that really the only choice open to the Germans if they won in the West? I know it's been objected that the German people would be in no mood for a new war, but the Red Army was in its infancy, and replacing the Bolsheviks with a puppet government would not take a huge military effort...