I coded a simple plugin for the SDR# to execute Multimon-ng and set some of the Multimon-ng parameters.
Visual Studio 2017. C#
Source code and plugin dll file https://github.com/OH1GIU-P/SDRSharpMultimonNG

Copy SDRSharp.MmngPlugin.dll from SDRSharp.MmngPlugin\SDRSharp.MmngPlugin\bin\Release to SDR# folder and add
<add key="Multimon-ng" value="SDRSharp.MmngPlugin.mmng,SDRSharp.MmngPlugin"/> to Plugins.xml file

sdrsmng.jpg