Queensland has probably similar heat problems. I don't wear black in summer, have now got a grey fully vented jacket with armour, vented gloves, Kevlar lined jeans, breathable lace up hiking boots. I have a Camel Back that I 2/3 fill and freeze, I then top it up with water, you need to put it at an angle to stop the lid from freezing closed. Mine has a very large neck opening and if you freeze 1.25 lt soda bottle of water you can use them to top up. You just cut open the bottle once it has defrosted a bit, and top up with water.You can also get a neck scarf that contains a water absorbing gel, once soaked it releases water, and does keep you cooler. You can also get a gel vest, I haven't tried one but I knew one person who swore by his.
Regards Martin.