I begun a SVN folder reorganization.
When the development started, I had kept two project separate: a generic MonoGame project and an Android oriented project. Inside the Android project folder, a solution with two more projects are present, one for development under Windows and the other for Android debugging.
These two projects refer to the main game project including it as an SVN external (green arrow in image 1), and are very light, implementing only the code required to start the application in theirs own environment (Windows or Android) and to interact with it.
When it's time to produce a new package for Google Play, firsts I merge the few changes to a previously created SVN branch (red arrow in image 1), fix the PEG number of the external MonoGame project and generate a new version number. Then I can proceed with the generation of the APKs (armv8 and x86) and publish them to Google Play.
Once published, I generate a SVN tag for the project (blue arrow on image 1).
Looking beyond (image 2), it is necessary to split the MonoGame project into two parts: a generic kernel project containing all the components that can be reusable in other games (eg: UI controls like buttons, screens, modal dialogs) and a specialized SlideFour game project.
Using this approach I can create new games without "reinventing the wheel" every time, and any fix or upgrade that I must apply to the components is immediately available to all the games.