Grab the turnip during the GP roll by hitting jump and throw at the same time.
Two useful things about this: it makes getting back on top MUCH easier, and you're closer to Topper when you land.
Also a nice tree jump.
If you roll cancel towards the right, sometimes your hat gets stuck on the railing.
Roll cancel needs to be at the ledge to get the correct angle afterwards
Shake to get the hat to hit the cloud