We had been beiing passed by everything all morning long. Semis, fifth wheels, travel trailers, motor homes, and of course cars. We had been doing 55 all morning. Speed limit is 75. We hadn't passed anybody the four hours or so we were on the road - everybody was whizzing past us like we were standing still. The semi we passed was old, rusty, nasty-looking, and probably couldn't go faster than 50 for whatever reason.
Thanks for all your replies. Even if I wanted to continue RVing I wouldn't be able to get my wife in one for all the tea in China. The accident took about three seconds from the first sway to in the ditch. Hanging upside down from your seatbelt surrounded by broken glass changed our lives.