Dakine wheeled coffins, mine & other people's too, seem to hold protect very well.
Pipe wrap around rails. Light cardboard & the Dakine cover or daybag covering the upper board's deck inside the coffin. Spray paint 'TOP LOAD ONLY' on the exterior of the case. Lock it w TSA padlocks. Get to airport more-early. Esp if outside the USA.
+1 with yankee, I have a Dakine wheeled coffin and my board hasn't suffered any damage from a couple of cross-country flights....but only with my Lokbox board. Haven't tried to ship a board with glass-on's, kind of a scary proposition. Don't bother locking anything, TSA will get into it....may as well make everything easily accessible.