Junior has suggested that if Green is cleared to play, Tim Paine should open (with Green at 7).
I'm actually totally on board with this if it's just for one Test. The triple role of keeping, opening and captaining would be too much to handle for a whole series or even back to back Tests at all IMO, but I think it's fine for a one-off given he's both very fit and realistically not likely to make game-changing contributions at #7 anyway. I also think his technique is well-suited to it, at least to the extent that I don't think he'll score less runs than he does batting down the order. When he was "one ton Paine" for over a decade, that one ton was in fact as opener.
If they're confident Warner and/or Pucovski will be available for the second Test (and I'm... not, really) then I think it's probably the best option. If he's going to have to do it for longer than a Test I'd look elsewhere though.
It still leaves the matter of the second opener, even if he does open. If Harris can replicate what he did the last time India toured (was actually Australia's highest run scorer, averaged 37, got regular starts and protected the middle order) I think we'd all take it. I think he's probably a worse bat than that output though, so it's a tough one. Usman would be ideal but it's not gonna happen.