It is usually the same 3 officials on the test matches with, as you say, a middle and 2 lines.
I'd be very happy with Poite on the final test, especially after his performance in 2017! However, I do think Gauzere is probably higher up the lists nowadays, unless his performance in the Wales vs England game went against him.
I do wonder if they will go 2 French officials, given the fact that they have had the chance to referee international matches already this year whereas the NZR and RA referees won't have refereed for 8 months. I'd go O'Keeffe, Gauzere and Poite in that order
Gardner, Williams, Berry and Peyper to do the 5 tour games in SA between them with the Japan game going to Raynal with Barnes and Adamson on TJ duty
Mixed emotions for me as I was supposed to be going on the Tour