Default parameter value in Dynamo without using the DefaultArgument attribute

As the title says, is there a way to introduce a default parameter value in Dynamo without using the DefaultArgument attribute?

I am trying to write a plugin that is independent from Dynamo (i.e. does not refer to any Dynamo DLLs), and has methods that can be extended/re-implemented by other developers (so they must be declared public), but hidden from Dynamo end-users. My approach is to have 2 DLLs: one is a platform-independent DLL, which includes the above methods, and the other implements Dynamo-related functionalities. I tried to use the System.Runtime.InteropServices.DefaultParameterValue attribute from .NET, but Dynamo does not seem to parse it, and instead the whole plugin does not show up in Dynamo.

Many thanks,
Nicholas

Thank you erfajo. Sorry I edited the questions, as I mixed it up with another issue. It is actually about the default parameter value, not about hiding methods. For the latter, yes I have 2 DLLs, one independent from Dynamo and the other dependent.