Dear All
Many thanks for the helpful advice. That gets me started. I may be in touch to obtain further info. In the meantime if you think of any other angles please let me know. Bornfreee, thanks your offer to come along - you would be great, but unfortunately another pilot here is already locked in.
Prepositioning AvGas might indeed be needed. So far my information is that the only airports that have avgas or 80/87 are Kupang, Denpasar, Malang, Surabaya, Jakarta Halim (possibly), and Palembang. But no where else between Palembang and Penang. I think Penang has it because I flew in a 172 there a few years ago. But surprised that Medan (or somewhere close to there) doesn't - I need to do more work on this.
Cheers and thanks
Ross