A lot of kite companys make what they call "golf bags", nearly every kite shop you goto will either have them or order them in for you. these can normally fit a couple of boards 3 kites and some other gear so there would be plenty of room to pack all your luggage in and not go over the 20kg weight limit or extra bag charges. also means you can keep all your gear padded and safe cause we all know airline staff dont care about the gear and just throw it around onto the plane.
These are just some examples to look at
http://www.cabrinhakites.com/golf-bag-2.htmlwww.slingshotkiteboarding1.ashop.com.au/p/856640/mystic-golf-bag-with-wheels.htmlwww.liquidforce.com/luggage-golf-bag.htmlGood luck with it all