I think you'd get more responses in the Florida forum.

Anything native, once established for a year, should be drought-tolerant. You might even try a Citrus tree.

But more generally, it is expecting a lot for any container plant to survive with so minimal of inputs, primarily water. Container plants live in a tiny, self-contained world. Their roots have nowhere to expand to if things should require it. Good luck. In this case, you're going to need it.

+oM

I would suggest a Crown of Thorns. They bloom almost year-round, can take full sun and require very little water. I am in love with them. I think it will do very well for you in the conditions you described and come in both lovely shades of pink and red.

Carol in Jacksonville

have a look at Carissa macrocarpa (Natal Plum) - but it is normally thorny. but i heard there are thorn less hybrids. don't know if it's easy to get it. it's very drought tolerant and is like a succulent. it is fragrant and fruit can be cooked into jams, but plant itself is poisonous. it's often grown as a hedge in tropics.

http://imgarcade.com/1/carissa-macrocarpa-tree/

it is suitable for container.

http://www.floridata.com/Plants/Apocynaceae/Carissa%20macrocarpa/875