Hi Longqi,
I'm not sure tourism is the way either. Are tourists really going to pay to go all the way to Kofiau to not see a snake? It's a tough one. Also, unfortunately, the trade routes are not nearly as elaborate as you suggest. 90% of the greens leaving Papua go directly to Jakarta (or Bali). Therefore, I think less corruption and better enforcement at this one hub would stifle a lot of the trade... wishful thinking I know... but maybe worth a shot?
Euan, can you elaborate on how the data is incomplete? Also, which Malagasy species are regulated through the use of eggshells? Is this method still used there? What data did you provide the ball python report?