Good to have you on the forums, Qyasogk. As you can see from the number of pages, we are quite into Dave's Galaxy.
As for your idea, I would prefer a border system based more upon the regional government ranges of planets, once they get to that society level. This is because outside of those planets able to support a regional government, any claims you have are hard to effectively cement. Sure, you can send in fleet, but your fleets have to travel for at least a couple days just to get outside the range of the regional government which really limits what you can do to enforce it.
And what do you do when regional governments overlap? In several cases I have players well within my established regional governments, and if I was to build them on my border planets, well that would bring alot of planets within my "territory"
