You should be fine. There are two queen beds and a pull down murphy style bed. They suggest the pull down for children around age 9 or 10 and younger. However, my 15 year old cousin just plain wanted to sleep on it and she fit. She said the mattress was a little thin but there is an extra blanket in the room you could lay down to make it softer if your 8 year old finds it to be an issue.
POR has two sections, mansion style rooms and alligator bayou. The rooms with pull downs are all in alligator bayou. They are very impressively themed and my family really liked them.
Have fun!