You many need to add another layer of indirection, so your unmanaged source files don't see the "contents" of the WrapperClass
class.
//WrapperClassWrapper.h
class WrapperClass;
class WrapperClassWrapper
{
public:
WrapperClassWrapper();
~WrapperClassWrapper();
//etc.
private:
WrapperClass *m_pWrapper;
}
And then you implement it in a WrapperClassWrapper.cpp which you compile with /clr.