Here's a map:
Prosser Family Campground
going to "satellite map" gives a better sense of the terrain
once down there, it's not confusing which way is into the water versus the only paved road out. It's back into the trees to get out. the part near the water is much more open plain.
you can see the paved road is not near the water except for the boat launch itself
for me, Occam's razor doesn't have her drive down a boat launch. not a girl who was conscious enough to charge her phone and text her mom about coming home.
Nor does Occam's razor allow the car to go down the one plausible route to the water without being witnessed
OTOH her car could easily get lost in the shuffle if a bunch of people were leaving, or even just her car went in the proper direction out of the campsite, someone offered to drive her or was holding a gun to her, and then instead of going the same way, took off on dirt roads