I would try Gulp Shrimp,Gulp Jerk Shads,and Gulp Minnows on a 1/8-1oz lead heads.2"FinSfish would work good too when fish are feeding on GlassMinnows.I know these lures worked for me down in FLA but I dont know if they would work in TX.Using jigs under a Popping Cork wouldnt be bad too.
BigJeff823 is spot on but here's a great lure that will score reds, trout and or flounder in South Padre.
DOA shrimp in NEW PENNY color - 1/4 oz model fished freeline mode under the lights and or during high slack tide near shallow to deep water drop offs. If you need to, add an Alameda style popping cork that has BB's inside and cast that working an inbound tide, casting past the lights and letting this bait drift slowly into the lights with a periodic pop and rattle of the float.
I use a lot of Mirolures M52R & M51R (swim baits that look like mullet) and prefer to fish at night casting the flats with a black lure. Best nights are during a full moon and considering your fishing South Padre island, get out there and wade the flats just off Boca Chica (across from the High School). Just wade out and start casting at sunup once you get into water around your knees (redfish). Wade further out to your chest and catch specks and or the occassional snook out on the flats. During the summertime, when the heat is on...don't waste your time fishing during the day, wait till the last few hours before sunset and or fish the first hour or two after sunrise. Mid-day, it's too hot but night time = best!
You can also drive over and fish the North Jetty on the island. There, I would recommend DOA shrimp in New Penny; 1/4 - 1/2 Rattletraps with chrome sides, black back; Mirrolure 52MR white belly, silver sides and black back; or 1/8 - 1/4 ounce red lead head jigs with shrimp tails of various colors. If the water is super clear, use an 1/8 ounce lead head with a clear body shrimp tail that is literally clear with silver sparkles inside the lures plastic body with a Chartreuse colored tail. This is a deadly gin clear water lure in the lower Laguna Madre and skinny surf zone water of the Gulf of Mexico.
The old South Texas stand-by bait....gin clear water, cast Johnson Sprite silver spoons 1/4 - 3/4 ounce in size. If the water gets sandy green and or sandy brown....switch to a gold colored Johnson Sprite spoon of the same weights. If the water appears to have a little brown stain....switch to a Copper colored Johnson Sprite. When casting spoons, always use a snap swivel to allow the line to spin freely without tangle. If you don't use a snap swivel, beware, your line is going to spin into a big mess and your casting and lure's action will suffer to a point, it becomes unfishable.