Since you are specifically pointing out Texas, when you get vehicle tags specifically for this hobby (which I do) with your call sign embossed on it, it also has printed in red letters on it "RADIO OPERATOR". Since there is no additional charge for these 'vanity' plates, one of the stipulations to getting the plates is that you agree to have Amateur Radio gear in the vehicle. Why? Because in an emergency, if all other communications systems are down, the police can spot you and ask you to become a relay point for emergency communications. This law, if passed does not impinge our vehicular use of said gear, only that we must obey all other relevant laws to said operation. KF5JOT is correct.