Seriously you can kite on pretty much anything.
SUPs are definitely good light wind fun. Good for tandem and handplants.
McDonalds trays are somewhat doable. They are way to flexy and break a bit easy though.
Also have kited on the hard bit of a palm frond. Could get fully plaining if you get a stiff enough one. The one I found was shaped a bit like a boat.
Its also good fun towing people. Not exactly strange craft but its good fun Doing kite loops turns out pretty sick.
The possibilities are endless.
Keahi