So, I found this ant-mimic spider along with a bunch of Crematogaster laeviuscula in Dallas. However, I remembered about it today when I saw one with the same ant species here in Austin today. When it walked, it even held its abdomen over its head just like the Crematogaster!
I know this isn't the best picture, but I'd like to get this spider IDed. My best guess is Peckhamia sp.
Thanks!