One of the first things we noticed when we bought this trailer is that it's very wiggly - any movement inside is keenly felt by stationary occupants. I debated more permanent and costly solutions like SteadyFast or JT StrongArm but when I learned about the Valterra 020106 Stabilizer I figured I'd give a pair of them a try.
I put the first one under the rear of the trailer. The previous owners had some frame reinforcement welded there and it made for the perfect spot.
Setup is pretty quick - unfold them from the included storage bag, brace them in place (the foot friction will stop them from spreading and collapsing), attach the ratchet strap and cinch it tight.
We were immediately impressed with the results. Though it's hard to quantify the improvement I'd estimate that 80% of the shake was removed.
We put the second stabilizer under the top of the stairs. While it doesn't reduce the remaining shake much, it does eliminate the springboard effect felt when someone enters or exits the trailer.
An excellent product and at less than USD 100 for the pair, well worth the money.