Board in board bag with some sort of soft stuff like towel, wetsuit clothes. In plastic bags if you have wax on your board. Keep it light because it's easier to carry.
Then have a big duffle bag. Northface Base Camp xl is excellent. put your kites in vacuum bags used for blankets. Pack kites in those, suck out the air. Pack into duffle with rest of gear. Use the compression straps on outside. Watch the weight 23kgs. I get my 9-12-17 m in the bag.
Technically the duffle is too big, but never had anyone call me out on it 10+ trips.
Pack your carry-on to maximum.
I've tried golfbag, roller bag etc. Above solution works best.