[Hersbird]

Is that what brought the Tacoma Narrows bridge down?

After reading the wiki article it says Aeroelasticity is what brought the Narrows down.
Yes this is the kind of thing I would worry about. In a car or bike with wheels at each end there shouldn't be a problem but on a single axle trailer already potentially with sway a problem, I just was wondering why we haven't seen boattail trailers since the earliest days.