How to arrange a cross platform c++ android / MFC git project?

Question

I am developing a cross platform multimedia editing tool for Windows and Android. After a lot of experimentation with various cross platform frameworks I pretty much gave up and decided to use Android studio with NDK for the android version and visual studio MFC for windows. Even with completely separate UIs I can still share 70% to 90% of the core C++. The question is how best to manage the code.

I was thinking of creating a base directory and loading it with:

1. My git file/directory

2. The android studio project (including Android specific C++)

3. the MFC projects (including various tests and windows C++ files)

4. a multi level directory containing all the shared C++ code

Then whenever I modify either platform's code or the general C++ I will use the same git repo to version manage (from the command line)

Does this sound sensible or stupid?

I am not sure android studio will let me put C++ files in some arbitrary directory but I know I can get visual studio to read them in from any where I want. So I may end up having to put all the common file somewhere in the Android studio source tree.

To provide a little additional context this program will be about 50,000 – 100,000 lines long and at the moment I am the only developer but hope to hire more someday. It involves audio, video, screen recording, ASR, TTS, 2D animation and perhaps shared documents. I am currently 1/3 of the way through a re-factor from a 30,000 MFC only version and one day hope to also port to Apple platforms.

Thanks

Andre'