Adding Mono 2.0 runtime for Unity in Windows

I wanted to add the Mono 2.0 runtime in the hopes that the IDE's compiler feedback would be consistent with Unity's. Unity bundles a Mono runtime, so I first tried to add that, but was unable. Then I installed Mono 2.0 directly and tried to add that, but was also unable. In both cases, it appears to be a simple matter of executables not being where Rider expects them to be. I tried selecting different folders to "add" to no avail. Error messages are variants of this in every case:

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Cannot detect any runtime at C:/Program Files (x86)/Mono-2.0: Could not find a part of the path 'C:\Program Files (x86)\Mono-2.0\lib\mono\xbuild'.

--- EXCEPTION #1/1 [DirectoryNotFoundException]
Message = “Could not find a part of the path 'C:\Program Files (x86)\Mono-2.0\lib\mono\xbuild'.”
ExceptionPath = Root
ClassName = System.IO.DirectoryNotFoundException
HResult = COR_E_DIRECTORYNOTFOUND=E_PATHNOTFOUND=80070003
Source = mscorlib
StackTraceString = “