git workflow for fully distributed mini-teams

I am trying to formulate (and understand) what it means to have a fully-distributed mini team workflow with git.

By fully distributed I mean theres no central repo -- not for pushing or even pulling; all communication is by email. By mini-team I mean: Not more than 5 programmers.

Heres a typical scenario.

There are 3 programmers A B and C who communicate by email who have started off from the same code base.

A's branches: dev, master, B, C B's branches: dev, master, A, C C's branches: dev, master, A, B

A's best practices (and invariants) are: I (ie A) develop on dev (or other topic branches). I only merge onto master; never commit. I never work on nor merge onto B and C. When B sends me patches I apply them to the B branch likewise for C. Thereafter I merge that branch onto dev or master. There are no tracking branches because there are no remotes -- no central repo. [not clear about this]

B and C have corresponding practices/behavior.

So the questions...

Is there a better way of doing things? Can some of these practices/invariants be enforced by scripts/options etc? What about checkpointing and restoring from botches?