Man, what are you doing to yourself, hope you are OK mate.
Alex I spent sometime in the NT and those portable car port structures are everywhere, they are very good and work a treat.
They will protect from the Sun an also provide plenty of ventilation
As for your Annex, mate take it out side and burn it. they are the most useless, hot, cramped, stupid inventions ever.
I have been around Australia for many years, and although one came with the Caravan it has never be opened, you can have it if you want
All my traveling friends hate the stupid things, and just drag them around in their vans for fun
and to add weight to there tow limits.
Take care Alex, my friend
Leon