Make APK with unique ID without compiling

There is such problem:

1) I have to use my our distribution service to give new builds of app to testers (no way to use HockeyApp or etc.)

2) I want to give unique APK file to each tester. But it is not possible for me to compile ~3000 APK files for every new build of application.

So I want to add some kind of ID to APK file without recompiling it.

(I need it to identify, if some user will share this APK file somewhere in web without my permission)

Example:

User downloads .apk file from my site => uploads it to some forum/website => I see, that somebody has shared my app in web => I download apk from that forum/website => I identify, who shared it (via unique ID of apk)