Eclipse RCP: implement feature separated from other code

Question

Let's say we want to extend someone elses (open-source) Eclipse 4 RCP application with our own eclipse-feature. Obviously, this feature cannot be stored together with the other code, but must reside in its own git repository. Unfortunately, the plugins of the 3rd party's RCP application are not deployed to any p2 repository. Maven is being used as a build system.

I would also like to perform integration tests of the RCP with my feature included. This is the structure that I am planing to set up:

My Gitrepository   
│
└───3rd party E4 RCP (Git repository as submodule)
│   
└───My Feature
    │   plugin project
    │   feature project
    |   test fragment
    |   integration-test fragment

What are your opinions about it? Is there any better or recommended way how to approach this problem?