I don't think it will fit in a standard luggage, especially the 5.9 (that means 180 cm.). Split in half, the two halves are IMO not less then 95 cm. (180/2 = 90, add the surmounting parts and I think you're close to 1 mt.). The biggest standard luggage bags are not longer than about 80 cm. (e.g. this one, it's the biggest of the Da Kine collection, http://eu.dakine.com/p/backpacks-and-ge ... r-100l-16w
). Usable internal width is normally about 40 cm., that means 5 or more cm. less than a standard surfboard.
I own an italian custom CKT carbon split board, 134x42. It splits in two halves, each one about 70 cm. (134/2 = 67, add about 3 cm. surmount). The two halves fit in my standard North travel bag but the width is the maximum the bag can contain and the lenght should allow I think no more than 10 more cm.