Of the options you've given, i'd go for the 5d3 with the 1.4* TC:
The iso performance of the 5d3 will let you get away with more with the TC on than the 7d will.
If you have the TC, you can always choose not to use it. If you don't have it, then you don't have the choice.
While muddying the waters probably isn't that helpful (sorry!); Have you considered getting the 2* instead? Unless they're making y'all watch the play in the dark, i'd expect that the 5d3's iso performance would be fine and it would give you the option of tighter shots, should you want them. Plus, at the end of the day, you'd then have that greater reach available whenever you wanted it.
I assume that you have the 5d3, 7d and 70-200 already?