or the ultimate, Aviso hollow boards:http://www.avisosurf.com/TechAdvantage.html
it all works.
Curious how the avisos hold up to the wave puntings during kiting compared to a sandwhich construction of similar weight.
If you make the sandwhich beam thick enough with enough dent resistance it should be fine. but in general large flat hollow carbon structures don't like to be jumped upon.
Figured a carbon skin honey comb core would be ultimate ideal, weighs nothing has good compression resistance and skins are fully supported...... it's just really expensive and not terribly good for shaping.