We're in the same boat. While our oldest sons are both out of college, our 3rd child is now entering HS and our HS uses block scheduling which means for every 1 day of school you miss, it's more like missing 2 days of "traditional" scheduling. There's no way we're pulling kids out of school for vacation. And because of the ages of our kids, our days of going to Disney during the school year are over for the next 11 years. But we've survived just fine in June, so I'll deal with it. But I can guarantee you that once the caboose baby graduates in 2023, I will not be taking trips to Disney World in June, July, or August.
And I understand your pain of letting go of the "commando" mode. I'm the commando in our family -- forcing everyone to get up for rope drops so we can have all of our "must do" things done by lunch time (that's another tip -- eat at off times if you eat at QS restaurants.) so that the rest of the day is our "icing on the cake" time. But when we were there last year, DH said the next time we go, he wants to sleep in more often and spend more late nights at the parks. <gasp> I will need some anti-anxiety meds to do that. I'm not sure I can *not* be at the parks at rope drop.

I have 11 months to readjust my planning methods and come to grips with it.