A bit of mental masturbation here, akin to the now imponderable question, “where in the hell is Springfield?”
We can tell by the clues given on King of the Hill, that it’s in the Texas hill country – north of San Antonio, but west of Dallas. And it’s (egad!) within commuting distance of Houston.
As well, as we see little of governance or university activity, we can be reasonably sure it’s not in the vicinity of Waco or Austin.
So, I repeat: where in the Texas is Arlen?