Well, 1604 is out - that's just as busy as I-10.
You can get off of I-10 in Boerne, TX and take Hwy 46 across to New Braunfels, TX
Here's a good route from I-10 West to South Padre that is 10 miles longer than going through town but will skirt SA the whole way. Here's a link that shows the route from I-10 out near Junction, TX through all the way to South Padre. (
The map and GPS marks the place where I-10 changes from 80mph to 75mph as an major highway change and that's where this routing starts from.)
https://www.google.com/maps/dir/I-10...26.1118401!3e0
You Exit I-10 at Boerne, TX like I said onto Hwy 46. You go east on 46 for 44 miles to New Braunfels (
wave when you go by the road to our house just .3 mile east of Hwy 46 and hwy 281 intersection). Once you get into New Braunfels you'll take Loop 337 East (
you go north to go east there) to follow Hwy 46 all the way to Seguin, TX. from there you follow a couple of roads to head south on Hwy 181 to I-37 at Mathis just before you get to the split to Hwy 77 near Corpus.
Super coincidence... we're going to Goliad State Park tomorrow for the week and we will go this exact same way from our house - it's just not so far so we will be leaving the route along the way.