Wakeboard-12yr old newbie (races alpine snowboard)

Hi All

I'm looking for the right wakeboard for my 12 year old son. He's totally new to wakeboarding, but races an alpine snowboard (carving board with hardboots) in the winter. This is mainly for fun, but it might also be good summer training for his main passion, which is alpine snowboard racing (slalom and giant slalom). He's not really into arials. He'd like like to "carve" a slalom course that we might setup. So, what's the best board for the above, one that will allow him to get started easily (generate some confidence) but last a while as he gains experience? What length? What features? FYI, we borrowed a neighbours board and he got up on the 2nd try and started to carve/cut some turns right off!!

Lastly, we'd consider buying a used board at this early stage.

Thanks for your help.

Julian