Through the spread of answers you can tell, it depends. It depends on lots of things.
We had a blowover in 2009. Tore the 5er right out of the 5th wheel. Spread the jaws, rolled & went down a 50'embankment, totalling the trailer. Windy day but the semis were travelling as usual. Huge gust caught us near the top of a mountain pass.
These days we are super aware of wind. Gusting 30 broadside is going to be our limit when faced with a choice at the beginning of the day. We are aware of where the weight is in the trailer. Most are much heavier on one side with the fridge, stove, all the stuff in the pantry etc. On a windy day, or maybe encountering wind, we travel fully loaded with water. For us that is 100gal & the tank is located down low right between the wheels, lowering our center of gravity.
Driving we watch the semis, look for flags, look for direction of ripples on ponds, look at trees & grass to get a sense of wind direction & speed. Many years working on the water brings a heightened sense of the weather around you.
5ers are so much better in wind than TTs. The thing is, when things go wrong because of wind they go wrong very quickly. Other than a few shudders along the highway miles before where we lost our trailer, there were few warnings. This was Wyoming. No trees, no grass, no flags, no water, highway signs used for wind warnings not lit. The last we saw of our trailer, the driver side wheels were off the ground. It was on its way.
Something else to think of. Those full height 13' 5ers are nice but think of all that additional windage they have. Try holding even a half sheet of plywood up in a breeze to get an idea.
Boat: 32' 1996 Albin 32+2, single Cummins 315hp
40+ night per year overnighter
2007 Alpenlite 34RLR
2006 Chevy 3500 LT, CC,LB 6.6L Diesel
Ham Radio: VP9KL, IRLP node 7995