There would be more prep needed in in getting the train ready. Car Equipment would have to make sure the cars have a decent air conditioning reliability. But even so, we all know how unreliable the R32 air conditioning was. Even with running the cars on an outside line, the sun beating down on the windows would make the air conditioning ineffective. I wouldn't even consider the Q being 50-50 underground/aboveground except on the first trip of the day since it's a long way underground from n/b PPk back to s/b PPk (I wouldn't count the 5 minutes each way on the bridge) and a long way above ground/open cut from s/b PPk back to n/b PPk where the a/c can cool down with regular outside air. Running the farewell R32 in this time of year is the best time. Finally, with the drama of the first week and the yard vandalism this week, there are many transit insiders, besides the Transit Museum President, who want this R32 thing to be over with this Sunday and be thankful it's over with.