We love an adventure and being adventurous, this just aint it for us.  We've had sex outside, but too many people get clipped on the side of the highway just changing a tire.  Wouldn't want to get hit, and the have the police explain to my family that I was on the side of the highway getting my guts dug out, and I didn't have any clothes on.  They look liked they had a good time so good for them.