Dr Steve,
If you don't feel an 8trailer can make my 12k empty 26k loaded max legal weight, and not go off the road because of violent sway, you're wrong! Yes a lighter truck, shorter WB than its 188", will go off the road, flip sideways sooner. You're still pulling an unsafe, illegal trailer from laws in my state at least. If you move more than 12" side to side, an LEO can pull you over, ticket you, RED TAG!!!!! You! You now can not move your rig until you fix the sway issue, or put the trailer on a low boy, car hauler or equal. This ticket carries as much punch as speeding etc.
Being over weight on the other hand, is not a moving violation! Better to be over weight, than get a moving violation due to sway!
I personally would not pull this trailer with a dual rear axle truck! Trailer is unsafe at any speed!
Mary