Okra and eggplant require only 70 to 90 days to mature, so you should be able to still get a crop of them by planting now. Getting them started in extreme heat will be the most difficult part. Although both grow well in the heat, when plants are small they can dry out quickly.
Both prefer loamy soil worked to a depth of at least 6-8 inches for growing. If the soil is heavy clay or fine sand, add compost or other organic matter.