I also grow peonies in the south, in zone 7a/7b. They're in beds with bearded irises and lilies, and they tolerate our summers fine. My plants don't go dormant until the fall.
The leaves do not burn, but the plants in full sun tend to lose their blooms sooner, due to the heat. I do have a sprinkler system, so watering them is not a problem.
I love the older scented doubles as well, I think they're just gorgeous. Be sure to provide them with support, since the stems tend to flop under the weight of the blooms, especially when it rains.
Annette
