I doubt they would do that for the reasons mentioned about. It would be like running a valet/coat check service and keeping track of who gets which items would turn into a major project. There would need to be somewhere to store them and give out tags so you got the correct item back. Better approach would be to purchase large items when you are exiting the park. Do you really want to carry the item around all day with you, even if you weren't doing any rides?