Using this, it is very easy to use a bottle jack under the axle mounting flange, and you will not have to schlep around a floor jack to change a tire.
Funny you should say this. I "schlepped" around a steel floor jack for a few years, but you can hardly lift one of those suckers. It's now aluminum and easy to handle. I have a longer list of schlepped items--generator (seldom used but like a parachute, good for the mental health) and air compressor.
I got stuck in the sand at the Big Dune just south of Beatty CA a few years ago--the terrain changed suddenly and there I was, TV and Airstream up to the axles. This had all the makings of skeletal remains, if you know what I mean. So I slowly deflated the TV tires and managed to "refloat" around 12 psi, down from 80 psi. Now what? The nearest service station was in Amargosa Valley, about 20 miles. It was a slow drive. Got there, neither station had air!
So now it's 30 miles to Beatty.
I ain't never goin' nowhere without a compressor.
About a year later, I dropped the trailer near Goblin Valley to do a little back country exploring and I sank into sand again. No sweat! Got the air compressor, so I quickly deflated the tires and moved on. However, when you leave the air hose in the bumper locker of the trailer
....and it's 40 miles back...oh, the humiliation.
If I'd had my gun, I'd have been an immediate candidate for the Darwin awards.
But I do like your device. Floor jacks don't roll so well on dirt, so when you jack it's a contest between the jack slipping off the axle plate or pulling the Airstream sideways. But if it were simple, all those other people would be doin' it and we wouldn't be so special