After some more searching, I think stumbled across the answer. It appears to be an…
# _Eriophora ravilla_ :
!Eriophora ravilla !Eriophora ravilla
Source BugGuide.net.
This species appears to have quite a diverse range of colors, and even thought I haven't found one that quite matches mine, the other similarities (the large abdomen, the stripe down the back, the four 'dimples', and the dark first leg segments) are enough to convince me. However, if anyone else can shed some light on this, I'd appreciate it.