Hi Connie!
Congratulations on your upcoming Walt Disney World vacation!
Disney's Port Orleans Resort - Riverside is a fantastic choice for a family of 5 with young children.
The guest rooms which accommodate the trundle bed are indeed located in the Alligator Bayou section of the resort. This area of the resort is included in the ongoing refurbishment, 1 or 2 buildings at a time. In the refurbished rooms, the trundle bed is now replaced by a single, pull-down wall bed with 3 large storage drawers underneath.
Current, unofficial reports I've recently read online indicate that Buildings 14 ("Preferred" room category), 36, 37 & 38 have completed their refurbishment as of mid-December. If you're hoping to have the opportunity to enjoy one of these newly re-done guest rooms with your family, I would suggest that you contact Walt Disney World's Vacation package reservations line at (407) 939-7675 and ask to add a 'note' to your reservation, requesting that your room be located in one of these mentioned buildings.
Walt Disney World Resort Cast Members always do their very best to accommodate Guest Requests, but keep in mind that they cannot guarantee that your request will be available for your exact resort stay dates. You can make your request known again upon arrival at Port Orleans Riverside during check-in. It never hurts to ask!
Wishing you a Magical time!
Kirsten