Great crop you have there.
I've always been told if you sprinkle a bit of Sulphate of Potash around the base of your tomato seedlings it helps the fruit taste better. Not entirely sure about that one though.
Also have you tried picking your tomatoes just as they start to colour and bringing them inside to ripen? I bring mine indoors and sit them on the kitchen bench, out of direct sunlight, and let them ripen. Mind you this becomes some what impractical when your tomatoes decide to crop all at once.
I think the very high temperatures and dry weather may also have something to do with lack of flavour.