Content Pipeline Reference Pathing with UWP Projects

I’ve brought in a library via NuGet that I need to reference in the Content Pipeline (the MonoGame.Extended.Content.Pipeline, but this issue is generic enough that it could effect any referenced DLL).
In order to use it, I need to add it as a reference in the Content.mgcp file.

The install guide (http://craftworkgames.github.io/MonoGame.Extended/installation/) explains that you can add a path manually, or use the Properties in the Content tool, to point to the DLL.
All well and good - it works just fine.

However, with a UWP project, the NuGet package isn’t located in a place relative to the solution.
Instead, it is found under your Windows user’s local folder (under the .nuget folder).
This is fine if I’m the only one working on the project.
However, if I check this code into Git and someone else pulls it in, this will not work on their local machine.

I’d love to use a system variable like %USERPROFILE% in the reference path. That way, it should work for everyone who downloads and run the software. But it doesn’t seem to be recognized.

Any thoughts from anyone on how I could path the reference in a generic way?