From my experience and observation, 70 mph with a bumper pull is really up there at the ragged edge. With a gooseneck or fifth wheel it's really just how fast can your truck go
There seems to be a lot more trailer wrecks in the past few years. I attribute it to trucks that can actually pull a trailer 80 mph. In the past you might be lucky to get up to 65.
Passing a semi going 65, when that bow wave hits the tail end of your trailer … well, you better have a really steady hand and tap the trailer brakes to straighten out or you're going to end up in the ditch with a big pile of splinters. Lots of truck dash cams on youtube if you don't believe me.
We were passing a pickup and camper trailer in our little car down by Crow Agency last summer, when he blew a trailer tire. It scared the sh1t out of me! Fortunately, it was his right rear tandem so it didn't swing over into our lane, and he managed to slow it down without going into driver induced yaw. We were going the posted 80 so he must have been doing 70-75. Too hot, too fast, and maybe too old of a tire …?