I've been to both AK and EP when they were hosting Moonlight Magic events---events that I was not attending. I think I knew when the events were, but never put two and two together until I saw the check-in locations. Yes, there were noticeable guests hanging around with wristbands, but I would hardly call it "pouring in." It was fine. After Hours might be a larger crowd, but I don't know.
If it works out best for your overall trip's flow to attend on a hard-ticket day, it will be fine. If it's not that big of a deal, it is easy to avoid. But personally I would not sweat it.