I think Bairstow could do a good job batting at 3.
8. Foakes/Buttler (can see the benefits of both)
If we put that team out, I'd actually be more worried about our bowling. Broad needs to up his game and Woakes needs to regain fitness and rhythm. I'm not convinced by any of the possible back up bowlers either. Roland-Jones was decent in seamer friendly conditions, but I reckon he'll be very easy to hit on flat Aussie pitches. Wood barely gets above 85mph in test matches. Jake Ball hasn't impressed me one bit in an England shirt. Finn hasn't been brilliant for Middlesex this year and he hardly has good memories of Australia.
The good news is that Starc, Pattinson, Hazlewood and Cummins all have injury worries and are unlikely to get through 5 tests.