I think you can´t find abalone in Spain, I hope another user can confirm that. Anyway, fishing selfish is prohibited, only profesional fishermen can collect selfish.
The planche that you developed seems to be great, I´ve just saw the photos. I believe that if you decide to sell it you are going to have a few clients in this forum. Nowadays you can find planches in shops but that one seems to be better and more resistant, and the flag is much visible, good idea.
The plaches you can find here are like this:
I think there are some post with home made planches in the forum.
Welcome and sorry about mi English...