I bought the smaller set from CW, and turns out there's not enough space between the tires for it to fit. Gave them to my BIL.
Saw a few examples online of people using a pipe clamp and a couple of 4x4 scraps.
A few minutes on the bandaw, and some time on the drill press...


Camper is completely steady now. This is a bit more expensive than ones using a threaded rod. You have to buy two Pony clamps, and a couple of 24" sections of 3/4 pipe (about $8 each!). But they will last a lifetime, and require no tools to install/remove.