That would work, I usually go the G-van route when I'm selling a bike and am splitting costs with the new guy cause there's always the chance the bike will be sitting in Salt Spray on the barge and stew at the docks for a while before it's picked up. If it's mine I make sure I pick it up right away and give it a good bath.
Since there's no direct service between Hilo and Maui Young Brothers charges you close double when go that route or Hilo to Kauai since everything gets cross loaded in Honolulu. Why not buy a bike on the Big Island and when you get tired of riding here ship it elsewhere?
There's a hell of a lot more riding here so it'll be a bit before you burn out, a serious trailbike (KTM, Husky, CRF-X. WR-F) with a plate will keep you entertained for years over here.