If you would stretch the period a bit up to 1921 you would have fighting in several places, Bavaria/Munich, Ruhr, the Baltics and Upper Silesia. The latter two would for sure offer more rural settings. I guess that it must also been some figting in villages and in the outskirts of Munich and other towns. I am considering to build a scenario around the third Silesian uprising May-July 1921, which also includes the Battle of Annaberg. There you have an interesting array of belligerents:
German side
Freikorps
Sebschutz(German militia)
German regulars
Indirect support by British and Italian troops
Polish side
Polish insurgents
indirect support by French troops