How to expose a managed class to unmanaged code without /clr

I need to expose a managed class to a fully native application, which cannot be compiled with /clr due to its dependences. I know that, if compiling with /clr was possible, I could just use gcroot. 

I have been told I can do this withoug hosting the CLR in my native application, which is a headache. Can anyone tell me with 100% certainty whether I would need to host the CLR for this purpose?

I need a managed object to be instantiated and not destroyed during the whole lifetime of my native application. This managed object is implemented using C# and I mean to build a C++/CLI wrapper. But no luck yet exposing the class instance.

Thanks!