You have the problem of dividing New Mexico along the Rio Grande which makes no sense considering the Rio Grande valley was the heart of the colony. Nuevo Mexico and Tejas were pretty similar regarding the mission system, the need for defense against the Plains Indians (and others), and economic activities. I'd put the border at the Continental Divide, leaving Northeast Mexico governed alongside Nuevo Mexico and Tejas while leaving Northwest Mexico with California and the Mexican Cession west of the Continental Divide. Using modern US/Mexican states, Sinaloa, Baja California, and Sonora would be assigned to a new "California" viceroyalty, also consisting of half of Colorado and New Mexico and all of Utah, Nevada, Arizona, and California, while the other one would be Coahuila, Chihuahua, Durango, Zacatecas, Nuevo Leon, San Luis Potosi, and Tamaulipas plus most of New Mexico, Colorado, and Texas. Louisiana might be attached to it, but it's best if it's governed from the Caribbean as Spain did OTL since the region was so economically linked to the Caribbean anyway.