Well I have seen 18 wheel trucks on it.....
BUT, personally I would not want to drive a rig towing a car over it myself.
I have made that drive many times in both a "Towed" vehicle and a couple times in "Lil Red". (My F-350 CC Dually)
You COULD do it. But I feel you would not enjoy the drive. You would get on the other side and be frazzled....
My suggestion is to go around on the Interstate and main highways.
Just my two cents worth...