FWIW
I get there a bit, often fly from Brisbane, I'm 86-90kg pending
5.3 / 4.7 is petty hard to beat 85/95 ltr wave board.
current set up is 5.5 - 4.7 90ltr
1 board 2 sails you can easily travel within weight limits etc on flights and makes the trip a lot easier than travelling with more gear ..
If its 'light' then thats a rest day! ..or as mentioned earlier, hit the roads its always windy somewhere in WA ,
Gero is hard to beat , but it does get some troughs that can skunk you ...but then when it turns its insane wind for a week!
Locals will tell you , and I tend to agree its not 'quite as windy' as it used to be , still 100 times more wind than Qld though! ....a 4.2 would be 'optional' nice to have but not essential.
It is weird sitting out the lighter winds that you would normally sail at home with , seems like wastage , and it is !
but thats entire 2nd set of gear you'd need, pack a long sleeve for the evenings ..for a Qld'r it can get quite cool when the sun goes down, and the water is much cooler than what you'd be used to here also.
TIP: Pace yourself..if you get a windy week , you don't want to blow out after a 6 hr session on day one! unlike Qld when it starts , it doesn't stop until it's dark ! , so you literally can sail from 1-7pm ! No afternoon storms to skunk it out, ..it just blows, blows and then blows some more , then eventually someone turns the lights off!
Looking forward to this summer ..planing two trips this year :)