Hi
Please find my comments below in-line:

Thank you for suggestion.
I've re-worked patch with MASTERDIR approach and shortened the patch to only angie and angie-module-geoip2 ports for ease of review process. If we can agree on this method, I'm ready to introduce all the others.
Thank you in advance!

Sorry for the delay, this time from my side.
From the Porters Handbook it seems that MASTERDIR is recommended for building slightly different versions of packages but in this particular case we have a bunch of almost independent ports that still share a significant amount of parts.
I see many similar approaches in the tree, please take a look at www/twiki* for example.
In my opinion this seems more natural and convenient than using MASTERDIR for this use case.
Please let me know what do you think? If you are still sure that MASTERDIR is the only possible viable solution, I'll take this approach.