Labeled as 1918 WS - 'MCA' ad present:
https://i.redd.it/lbseg0jltwd61.jpg
Merely coincidence, I'm sure... but seems like the opening day '20 photo shows a team of guys preparing to change out/clean/paint over(?) the 'John and Arthur' automobile ad... in fact, the 'Arthur' is either 1/2 way gone or 1/2 way completed... same appears to be the case with whatever was above the Hotel Commodore ad. Anyway, is it possible the opening day photo captures (at least some) ad changes underway at Fenway? Not sure how it fits with the WaJo date, but i'd image the corroborating photo you're looking for is out there...