Sounds like an interesting and adventurous trip .
Assuming your PLB is registered in NZ then you will likely find that you can add extra contacts who may know where you are further to the 3 provided for on the beacon registration form (or if registered already, email them the extra contact details), and they do not have to be NZ contacts. So, for example, if there is someone in SE Asia able to keep closer track of your itinerary than your normal contacts can, you can add them. If you do that, make sure you get any redundant contacts deleted from your registration when you get back.
If you are feeling geeky, somewhere on the COSPAS/SASAT website there is a little program that will disassemble the 15 character hex code on your beacon so you can see the country code, etc. Also documentation as to what all the positions in the disassembled code mean is on the site somewhere too. Of course, if you are extra geeky, you can disassemble it by hand .
Have a good trip.