I wanted to add to this as we just got back from our trip.
We went from Polynesian to Universal and setup the trip with Tony. We ended up bringing our own rear facing carseat but used his two booster seats. He did have rear facing car seats but it was giving my wife anxiety not knowing which kind and if they were age appropriate. We simply buckled it in and took it out when he dropped us off. Universal's lost and found held it at the front for us and we picked it up when we were leaving the park.
As many people have said before, Tony was great. He was easy to set everything up and on the way back to our resort he took us by ChickFila and Walgreens. He is a great guy and in the future, if we ever need it, we will use him.