We just returned from the Wonder.
We had brought some juice boxes and a few waters to have in the room. Plus a bottle of the premixed Margarita for mom & dad!!
We kept a ziplock bag of ice in there and it kept everything very cold. It took until the next morning to get things cool but once they were cold, they stayed that way.
Our stateroom host Brian was very accomodating. We left ziplock bags out for him and he filled them every time he brought ice for the room.