Once you get through Las Cruces, NM, (where I live) and El Paso, TX on I-10, continue on to Fort Stockton, TX. Stay at the Ft. Stockton RV Park (excellent little home-style restaurant on site). Then go south on US 285 toward Del Rio, TX. Stop at Langtry, TX where Judge Roy Bean, the "Law West of the Pecos" lived. Then on to Del Rio--stay at Lonesome Dove RV Park. Then on to Alice, TX (277, 44) then south on US 281 to McAllen. Stay at Tip O'Texas RV Park in Pharr (touches McAllen). The roads are great, just a lot of them with nothing to look at but desert fauna. We drove that route in March and there is virtually nothing to impede your progress. Safe travels!