Hi Jon,
I am not sure I can be a lot of help in this area, but which installer software or toolkit are you using? I have some lite-weight use of Microsoft Visual Studio installer projects back in 2010; which appears to be a separate download in 2015 (Microsoft Visual Studio 2015 Installer Projects). A number of our product installers we use are built off a framework over WixToolset (some Visual Studio integration information here: Working in Visual Studio (2015)).
I would think the installer APIs would provide either a Product or Registry search capability either directly or under a utility class (possibly requiring additional elevation), but my hands-on knowledge here is quite limited.
Bob