The moderate that sleeps five is Port Orleans Riverside. This info is copied from Deb's site:
The Riverside Resort has 2,048 rooms, making it the second largest "moderate" resort on the WDW property, after the Caribbean Beach Resort. As mentioned, the rooms are divided into two sections, Magnolia Bend and Alligator Bayou. Most rooms contain two double beds, although some king beds are available, and some rooms have a trundle bed as well. The rooms feature two pedestal sinks, a bathtub/shower with a retractable clothesline, a remote-controlled TV, a dresser, a table with two chairs, and a small luggage rack. Lighting is ample for reading or working, and a small safe is provided for storage of your valuables. Most rooms sleep four comfortably, and some rooms will sleep five.
It is the only moderate with trundle beds. The deluxe resorts have a daybed a child could sleep on, but really for families bigger than 4 it is difficult to find one room accomodations. Can you do two adjoining rooms? Is one of the kids an infant who would sleep in a port a crib?