It's been a few years since I hauled into Oklahoma....but we were never questioned at all there. Even stopped a time or two and unloaded and walked the horses, at road side parks. Got a few funny looks, but never anyone of authority anywhere. might be a lil stricter now tho.
As for brand inspectors in Texas...I know we have someone that gets paid for filling that possition.....but in the last 15 years sellin cows at the salebarn.....I've never seen the man.