I think it would be a cool addition to the game if you could use the item wheel while sitting (not the emote). For example, you are sitting on the side of your boat and you use the item wheel to pull out your fishing rod and start fishing of the side of your boat. Even playing instruments would be cool. I think this would also be a great addition for screenshots and "role players". Not only could they add things to do while you sit but even add more areas to sit. There could be benches added to certain places in islands or even just sitting off the end of a dock.
Note: This is ment for when you sit in a place where it gives you the option to "sit", not the sit emote you do from your emote wheel.