I looked a bit at Puroland, as I hadn't heard of it until now.
Definitely should have a themepark sort of theme right? Or at least parts of it? There are theme park items in the game as well~
You could make a stage, or an area to meet with Hello Kitty, but it being a cut out stand to look like Hello Kitty, with a couch and camera.
Next to the clothing store, you can have an outdoor clothing store but with Sanrio clothing. Merch store near Timmy & Tommy's. You can make a lil castle area for the entrance maybe?
Maybe use the moon seats and make a rainbow road towards the stage.
Do you have access to the Sanrio items at all? Like the Hello Kitty items, Kiki & Lala, Pompompurin & My Melody items? That would make things so much easier! You could have parts of the island centered to different Sanrio characters, that would be cute.
A cute pinic with plushies would be a cute idea also. An outside resturant with the sanrio items? Since most are just tables and chairs.