Finally got a word back from the experts! I didn't hear from TPWD, but one of the aquatic specialists in the biology department (the guy that actually does the fish identification lectures) ID'd it as a warmouth. Here's his reply:
"
Kevin:
I apologize for the delay in responding. I read your email, wanted to say more than “It’s a Warmouth”, but then got distracted.
I tend to put high priority on “Fish ID” type emails. It is not a bother. I enjoying do this.
Warmouth: Striations on the head (“war paint”) is one of the characteristics. I agree with you that only three are apparent, but I see a little bit of the bottom one and a little bit of the top one for 5. Color patterns aren’t always the best characteristics. Color patterns differ between male and females, can change during reproductive season, and can change when stressed. Lots of variability.
Another characteristic color pattern is the red (a see more of a red tint) behind and slightly above the black operculum spot (ear spot).
Sunfish vs. bass: Bass tend to be long and skinny, whereas Sunfishes tend to shorter and thicker (deeper body). To make this quantitative (and measureable), body depth usually goes 3 to 5 times in standard length for basses, and goes 2 to 2.5 times in standard length for sunfishes. Obviously health of the fish can affect the measures.
Combining body form with dorsal fin configuration (as you noted below, spiny dorsal and soft dorsal fins are joined to form almost a single dorsal fin in sunfishes, basses dorsal fins are almost separated to weakly joined), we can pretty much separate sunfishes and basses into two separate piles.
Among the sunfishes, it’s understandable on why Warmouths are confused more often with the bass lineage. Without double checking my facts (going off memory), Warmouth represents an older lineage of sunfish. As such, it is more closely related to the ancestral lineages of basses; therefore, it retains more of the ancestral characteristics (bass-like, tend to be more longer and skinner than other sunfishes).
Tim"
Looks like we all learned a bit more about warmouth on this one! Haha