Hi Jamie,
Taking advantage of free dining is great plan (and one I wish I could do!). We, too, are a family of 5, and there are many options available to your family. If you click
here, you can explore some of the suggestions. I'm going to add to the list that
Port Orleans Riverside, a moderate resort, is an option for families of 5; it has two double beds as well as a trundle bed. Since it is a small trundle bed (35" x 65"), it is recommended for children under 9 years -- but that should work for your youngest.
Similarly, the
deluxe resorts are fine for families of 5. The exception is the Animal Kingdom Lodge (suites would work) and the Wilderness Lodge (deluxe rooms would work) where the rooms are traditionally for families of 4.
Happy planning! Please let us know if we can help again.