older model s came with free lifetime supercharging. I have mine. I'm tempted to go. S Padre Island isn't going to let you sleep on it in your car, I would guess. Are there campgrounds nearby? Only 2 70kwh superchargers on the island. I will watch that video.
so what did you do after the 3 day delay? I ended up not going all the way there from the west coast. I need a one week delay, then I could torture myself with considering it.
Get/make some magnetic window covers. I couldn't find any when I drove cross country spontaneously so I just got a bunch of the cheapest black pillow cases and some binder clips.
Park literally anywhere not obvious, it is only one night. I am not sure how charged up you need to be to maintain a comfortable temperature. 5%? Just go and problem solve on the road. You'll be fine.