I had very similar problems with peppers that I planted later in the season. But the peppers I planted early (before extreme heat) are thriving. Larger plants can handle the heat much better, so if you are transplanting into extreme heat, maybe it is a good idea to wait until the plants are a little larger and less sensitive. Also I did not harden the young plants on top of the landscape fabric before transplanting, which would be better considering there is a temperature difference.