Without any stabilization, you have only the wheels and the hitch jack touching the ground. You will get movement under this setup. There are many products on the market that increase stability and decrease movement. The first I would recommend is a pair of BAL X chocks, which are basically a set of scissor type metal pads which tightly contact the tires (between the wheels on each side), and greatly reduce the movement of the wheels rocking back and forth. For me, this reduced the movement about 75%. The remaining movement can be pretty much eliminated, so I am told, by stabilizing telescopic bars that attach under the frame and use the triangulation principle to eliminate just about all movement. Several brands are good ones, and my personal preference (on my wish list) is the ones made by Plug-it-right. Steady Fast is also a popular brand. None of this stuff is cheap, but is about the only way to partially or completely eliminate the movement. Hope this helps.
2003 Ford F-350 V-10 Crew Cab 4WD Long Bed
2004 Jayco Designer Medallion 29 RLTS 5th wheel
Bill, Gayle, and Mindi (dachshund)
Retired at last !
Nothing is foolproof to a sufficiently talented fool.