Taken from Texas Traffic Code (The book with all the stuff u can be written tickets for):
§ 502.404. OPERATION OF VEHICLE WITHOUT LICENSE PLATE OR
REGISTRATION INSIGNIA. (a) A person commits an offense if the
person operates on a public highway during a registration period a
passenger car or commercial motor vehicle that does not display two
license plates, at the front and rear of the vehicle, that have
been:
(1) assigned by the department for the period; or
(2) validated by a registration insignia issued by the
department that establishes that the vehicle is registered for the
period.
As you can see it states only that the plate has to be on the front of the vehicle...no specific place.