NuGet has an excellent feature that allows you to build a debug package that includes symbols by simply adding the "-Symbols" parameter. The somewhat controversial part of this feature is that it includes a complete copy of the source code to help with debugging.
Good News: NuGet 3.0 will include an additional command option for "-ExcludeSourceCode", allowing you to build a symbol package without including the source directory!
ExcludeSourceCode Description: "Determines if a symbols package should exclude sources when created. Only useful when included with -Symbols."
How soon will 3.0 be released? We are currently on Beta 2, so hopefully soon!