I also have not been during that week in a long time (1997, to be specific), but I’ve been at 4th of July and Spring Break in the past few years. As long as you’re adjusting your expectations appropriately and don’t try to do too much then you’ll have a good time. Go in with the mindset that this trip is going to be different, and you’re not going to do as much but what you will do is still going to be great.
Do what you can get early FPs for, and use the Lines app. Since you’ve been so many times then I’d advise that you not try to do any huge attractions and maybe just focus on the more atmospheric stuff… see the details and shows and other things that are only there at this time of year. If you are they type who gets anxious thinking about what else you could be doing then 100-120 minutes spent waiting in a line could be very difficult to cope with, so maybe save the roller coasters (and other major attractions) for another trip when the lines won’t be stretched down the midway.
As far as midday breaks go, this is one time of year when I actually wouldn’t plan for them. The weather is going to be more conducive to a long day outdoors, and the lines for everything will be so long that you really need every minute of park time. Also, transportation (even in your own car or an Uber) can take forever, just due to the volume of traffic on the roads. I would, however, suggest a non-character sit down meal at some point during each day. Seating at any of the QS places is likely to be very, very difficult to find and you’re going to want to eat and have a moment away from the chaos and crowds. Also, most QS places will have long lines, especially at “normal” meal times so if you plan to eat there make sure you build in the wait to order when you make your plans.
Most of all, be flexible. Having a pre-made TP is good, but you can’t be married to it. You’ve got to be ready to shuffle things up. Have your walking speed set to “very relaxed” and avoid long cross-park treks whenever possible, because simply maneuvering the crowds can make it take much longer than usual to get from point A to point B.