As you can see, personal choices very a lot, just like what kind of RV is best. We go to the Fort several times a year, and some times if we have only a few days, we will stay at the Wilderness Lodge. We have never used any of the "regular" dining plans. We purchase a "Tables in Wonderland" card annually, that gets us a dining discount, but it is only worth the cost if you visit WDW often. That said, even when our kids were little, we would take pre-prepared or pre-packaged breakfast items with us and munch while waiting for a bus or boat. We make reservations in advance for one big meal/day if in parks, mid-afternoon that serves both as lunch and dinner. If we get hungry later, we will just get a snack. The Trail's End offerings have been mentioned by others. But also consider that many other "fast food" places are available by a simple boat ride. For example, Roaring Fork over at the Wilderness Lodge which has burgers & pizza stuff. Additionally, you could go to either of the Trading Posts at the Fort and buy lunch meat & bread/rolls for sandwiches or purchase other less expensive meal items.
In our style of doing Disney, we cannot imagine using all the meals of a regular dining plan. But, that's us. Additionally, the dining plan would have us eating more, thereby decreasing the time actually enjoying the park.
Having been to WDW in all seasons, we would agree with others about the Florida heat in the summer, especially as it relates to kids. Consider an afternoon break, either back at the Fort, or a cool lobby area like the hotels on the monorail loop. Everyone should consider a mid-afternoon break in the heat, and drink plenty of fluids.
Have a great trip.