We take a loop that goes on the east side of SA when we go to RGV. Don't remember # of it though. I know you exit/veer to the left. A lot less traffic. We use it whether we're pulling RV or not. Have several eating places @ Rigsby exit & WM.
We took 1604 on west side off 281 when we we to Garner SP & it took us forever! Lots of traffic & many stop lights plus construction. Would never go that way intentionally again! The only blessing to going that way was we had blowout & there was a Discount Tire real close & even had room to park RV while we waited for tires to be delivered.