HiGuppyboy,
North QLD winds tend to be fairly light especially if you are in the Southern part of North QLD. I would not go under 142cm. You could also look into a slightly wider board like 44-45cm wide which will help a lot. You should also consider getting a board around 150cm or more to start with, then look into getting a second small board like a 136-138cm later. At that point, you can keep the big board for light wind days and use the small board for the moderate and strong wind days.
Have a look at our kite and board size calculator here:
www.kitebud.com.au/how-to-choose-a-kite-size/
Hope this helps
Christian - Kitebud