I have grown tomatoes in large pots and never seen blight. I do see a lot of insect damage which is what discourages me. And I love using H2O2 (Hydrogen peroxide drops added to my watering can). I also know that tomatoes are heavy feeders. I think that is the other problem I have. Finding a good fertilizer. Would worm castings be a good fertilizer. I have a worm bin and have used the worm compost with amazing success on newly potted plants and with plants going into the ground.
I have great luck with bell peppers, blueberries, and most herbs. But again, they are all grown in pots/containers. I don't know how many of those are susceptible to root knot nematodes here in Florida if I was to grow them in the ground.
Everyone thinks living in Florida is great because of our year round growing conditions, but that is negated by the insects and plant diseases. So it really is a matter of finding the right plants to grow successfully here. I do think heirloom plants are a challenge to grow in FL.
Elaine - Could you please tell me again what three sprays you keep on hand?
