IMO, there are too many factors involved, like wind direction, roadway surface, bridges over rivers which the valleys create wind tunnels etc .
I would think an empty box (like a TT) would be more susceptible to being blown over opposed to loaded box.
It would probably help in a windy situation to have a full tank of water keeping the COG lower.
I noticed a big difference in hauling truck campers with slides and no slides. Slide model had basements, making the unit taller and YES I could really feel the difference in crosswinds.
IN any RV type : If winds are more than a steady 25-30 mph, I feel more comfortable holding off till they die down. Too much chance for a strong gust from the wrong direction to take me by surprise.
Big box store parking lots sometimes rock ! :B