If you get the BAL Lockarm stabilizer struts, you only have to buy a pair of them and are cheaper.  You might find a pair at the rear is all you need.  I installed a pair at the rear only and it really helps.  I mounted them to the underside of the bumper and get some fore/aft reduction in motion as well as side-side.
Adding a pair of jacks just ahead of the axle under the frame can help too.  Having a larger surface area under the jack pads can also help on some sites, like a piece of 2x8.  Some TTs simply have a weaker floor structure and frame.