when i worked at bonsai nursery brisbane, we would send orders to bunnings all over australia but Japanese maples NEVER went any further north than the sunshine coast on strict orders, not to say that one or two might have slipped through from time to time for the poor folks up north that constantly requested them
but there is a good reason for this and that is simply because they just didn't do well in the heat. in saying that, i really do hope that u guys can prove me wrong and find some cultivars that thrive here but until i see it for myself i won't be holding my breath. i hope i'm not sounding negative but i would hate to see anyone else have to loose quite a few bucks in the process. but i am hopeful and wish you guys the best of luck.a couple more things to consider for you guys that are going to perservere is that sun protection is a must but also try and find a spot out of wind because even if you have them under shadecloth etc. a hot wind will do as much if not more damage than direct sun and a common problem we would see at the nursery was root fungus/root rot and i was always suspicious that people would see the leaves drying out and think water water water..!! so i wouldn't keep them to wet, once those leaves are burnt no amount of water will bring them back to health! good luck guys i am eagerly awaiting a pm saying guess what... we told ya so! cheers
taking the top half of trees of since 2005! 
