When we t-boned a vehicle a couple years ago, we had more than enough hitch. Rails and mounting system were rated by Reese for up to 24K. We had just installed a new 20K Reese hitch (replacing the previous 16K Reese hitch) a couple months before this happened. (Our trailer, a BC 3950FB, weighed right around the 16K GVWR). The hardware used to hold down the mounting rails, however, were questionably not adequate.
Note that the rear rail sheared the mounting bolts and pulled up from the bed. The front rail stayed in place, but the pins holding the hitch to the rail pulled clean through the hitch mounting lugs.
Here's another view:
Here's what the frame-mounted base looked like (this is the rear part, behind the axle). You can see it flexed some before the frame rail bolts gave way.
I contacted Reese asking if they'd like to see pictures and they said yes. I never heard anything back from them. I'm sure their legal department would probably suggest not replying afterwards. Truck was totalled, trailer was eventually fixed and we moved on. (We have a B&W hitch in our current tow rig now).
FYI, this was a 2013 Ford F-350 DRW, so plenty of truck.