After giving Lechuck the fake turtle, return to the mold stone and get another one! Use the 2nd fake turtle on LeChuck on the beach to trigger a bugged cutscene. (don't worry, you wont get a gamecrash)
After your rubber mast is installed, go to the island it came from and the tree will still be there!
If you don't like this post, please go make another one yourself and show me where I can improve my language.