When we did this in June, I didn't notice any Photopass Photographers out, but they may have been. I was pretty oblivious taking in the emptiness of the park! Even a few hundred people dissipate rapidly in the MK, so it isn't like your pictures would look anything like they'd look even an hour later at park opening. If you wanted to have as few people as possible in a picture, I guess you could get to the MK super early, like 7:00 a.m., to be in the front of the breakfast line. As a non-morning person, that wouldn't be worth it to me though, just based on how few people are there even with a 7:40 arrival.
Hundreds is better than thousands, and it's not nearly as crazy as a regular RD since the crowds disperse so easily.