Axle and trailer mfg warn not to jack from axle because unthing owners placed their jack towards the center of the axle and bent it.
I have a 12 ton hyd shortie truckers special that has a cradle welded to the top of the jack that cradles the axle tube on a std leaf spring axle system.
Placed under the axle next to the U bolt works great for just lifting one end of a axle (1750lb-10k axle tubes) for changing a flat or R&R one wheel.
Now if I want all wheels of the ground on a long trailer then I use two jacks to lift one side at a time. Having bent the frame with one jack on a fully loaded 34' flatdeck I now place the jacks next to the farthest aft and forward spring hangers.
Whatever method your planning on using to change a flat tire on the side of the road do a dry run at home. Living next to the mother road (old US-66) I've helped lots of trailer owners (rv and non rv) who never tried their system at home.
One guy thought he had enough cribbing to raise the side of the trailer to change a flat tire on a 38' triaxle LEQ with 7k axles. I slid old shorty under the end axle tube and raised the flat tire of the ground without raising the trailer. He said a shorty hyd jack was now on his short list.
