IF you are only jacking one wheel position at a time then resting on the tongue jack and wheel chocks on opposite side is safe.
You only need to jack wheel just off ground so you can spin it.
Under the spring perch is fine.
Mfg. place cautions about jacking on axle tubes because some dim-wit placed a jack under middle of axle tube, bent it, wore our tires/bearings and then blamed MFG.
Jack up wheel
Adjust star wheel to tighten brake shoes while spinning tire until you can not move wheel
Back off adjustment on star wheel (loosen) until you can just spin wheel and hear a slight drag of brake shoes (wheel should turn at least 1/2 revolution then stop)
You will then need to readjust brake controller due to brake shoes engaging drums sooner than before