you would certainly want your 11m.
as for the airline baggage restrictions, i know Jetstar let you check in 20kgs of luggauge. You can then carry on another 10? kgs. i know the also have a length rule, i couldnt take a pair of snow skis on, so you need to check that out.
so pack the kites, a couple of boards and a harness, and then tshirt and boardies, thats all you really need