POR trundle room is your only option in the Moderate catagory, and no Value will fit five. That said, you do have a few other options.
You can fit 5 in most Deluxe rooms. You can also look into one of the Villas (Boardwalk Villas, Villas at Wilderness Lodge, etc.). Both of these options are much more expensive though. You can also rent points from a DVC member for one of the villas, but that can be a bit complicated. Also, dont' forget about the Swan and Dolphin, good rates can sometimes be had at these two hotels.
Another option are the cabins at Ft. Wilderness. They sleep six and have a full kitchen.
The last option is to rent two rooms (and request connecting) at one of the Value resorts. This would be about the same or a bit more than the trundle room (depending on what codes you might get). But you then have two bathrooms instead of one, and a separate room for the kiddies at nap time!