Hi there down under, I am from Germany and will be travelling end of dec from Frazer Island to Sydney by RV. I have a 16m2 kite for windspeeds from 10-20 kts and a 10m2 for 18 – 30 kts. I would prefer to carry only 1 kite with me. I guessed that the 16m2 would be the right choice for the vast majority of wind conditions I will encounter in NSW. What do you recommend?

I would really try and bring both, you don't want to be sitting on the beach or pushing your 16m2 in perfect 25 Kts seabreeze.
If you can fly both on one bar rolling up 2 kites together doesn't add much space or wieght

Surely you can fit 2 kites in your RV! I fit 4 kites on the back of my motorcycle