We have used Padre Balli...essentially, it's a large, reconverted parking lot...there aren't 'spaces' as such, just markings on the asphalt...also, because it wasn't designed from the outset for RV's, you may have to do some head-scratching to figure out how to get the rig parked so as to reach 'your' utility hookups...right between the parking lot and the water is a 8-10' high sand berm...no amenities as such (pool, tennis courts, etc.)...it does have a fishing pier with a restaurant/bait shop...location, location, location!
you should find lots about mustang islandon here...went in once, without camping...just open to the ocean, with parking near the water...no trees or anything...sand and more sand
Glenn and Toni
2019 Jayco JayFlight SLX8 264 BH
2019 Ram 1500 5.7 3.21 gears
Reese round bar w/d with sway control