I feel fairly certain that this is the Kordes Purple Rain. The habit's right: It's a short rose (under 2 feet tall), but a sprawling one, much wider than it is tall. The blooms look right too: small blooms with a rosette shape. I'd be tempted to grow it in a big hanging basket.
A lot of purple roses tend to be pinker or quickly fade to pink in the warmer zones, and you're certainly in one of those. My Ebb Tide was a nice dark purple in the shade. Now that i've moved it into the sun, the color isn't very exciting (or very purple) at all. Maybe your fall flush will be closer to purple.
