The system you described is similar to municipal governance in Canada. Our municipal councilors are not elected by party affiliation. Their coalitions form, break, and re-form based on the issue put forth to council.

Initially the local TDGS should have a simple constitution to govern itself. And writing that constitution will give early TDG builders the practice for the new culture the TDG needs.

As the TDG gets bigger, it will need some new structures that go beyond "simple." It can certainly experiment with the ideas you have presented.