While I would like to think the first two episodes this season are an uberleg, I'm siding with the two legs with no rest period interpretation.
First Phil said there were 12 legs before he released the teams in Palm Springs.
Second, the clue directing teams to Shelly Beach made reference to a pit stop and that the last team to arrive may be eliminated.
Third, the Express Pass was award at the end of this leg, as it was at the end of the first leg of TAR 17.
The only difference is that there was no rest period between legs 1 and 2.
So while these first two legs emulated an uberleg to the extent that we're debating the issue, I still think that unless we find there are to be 13 episodes and 13 hours, then the 12 legs cover 12 episodes and 12 hours (as reported by The Futon Critic).
The other thing to keep in mind is that WRP has all but abandoned a standard rest period or 24 hour multiples. We've increasingly had odd-length rest periods, and increasingly, we don't even get told what the departure times are for particular legs. So given that, two legs with no rest period inbetween, as opposed to an uberleg, was due to happen. (You will note teams weren't even given money amounts for these first two legs, or at least I never heard any amounts or saw any teams with US dollars at any point in either Palm Springs or on Shelly Beach.
(I will note that Masem, who does the primary editing of the Wikipedia pages on TAR has changed their assessment and are now treating Shelley Beach as the end of the first leg, and Broken Hill as the end of the second.)
One other point on the TBC -- we had a similar issue during TARAS in Poland, where some teams began the next leg before the trailing teams completed the first leg in Poland. I think that may be the most pertinent precedent for how these two episodes were edited.