So in other words, they've gotten no further than Spring last year.
The situation is this:
Schmier will do whatever.
Mille wants to tour for six weeks minimum and hit as many cities as possible.
Tom will only tour for a maximum of three weeks because he doesn't want to be away from home any longer than that.
To me the answer is simple, do several three-week stints at different times of the year so Tom can go home in between. Might be more expensive with multiple flights, but unless they can change either Tom or Mille's mind, that's the only way I can see it working.
10/12 Black Sabbath
18/12 Black Sabbath