Thank you very much to theplank for your input. Since I wrote that last post, I had in fact downloaded the openstreetmap maps. I have now successfully made a new mapset with my southern States of Australia plus the Egypt & Jordan maps.
All maps are now in my Garmin - I have all the caches that I would like to attempt while I'm on my trip ready to send to GPS just before I go. I am excited that this will be my first caching experience outside of Australia.