As I'm right in the middle of a trip from the Western US to the Canaries with an 8'3 bag (plus another checked bag and a heavy carry on), my advice would be... don't do it.
There are no direct flights in this case so I'm doing a multi day layover and visiting family. I'll end up w/ two board bag charges totaling about 200 euro (pretty reasonable) and round trip taxi costs of 190 euro (Nobody I know had a car big enough to transport the bag). YMMV... In this case Condor airlines shines and will still transport bags up to 300cm and 30Kg is included, I don't give a crap if they can lift it. Two separate board bags would be ridiculous.
Can't wait for those V2 - V3 parawings to get to market so I can get back to a sub 6' board bag