I don't think this is an overkill. I know that WPF app can reference the Silverlight 2 class library but it doesn't work all the time. if you are testing with small project that has only two or three classes then it will work. but it won't work if you have
a lot of classes and folders in Silverlight Class Library.
I used to get the error below.
"Unknow build error, 'The located assembly's menifest definition doesn't match the assembly reference. (Exception from HRESULT: 0x80131040)'"
That's why I started using the Project Linker in my project.