I had my car up on two at the rear today while inspecting the rear end of my car.
I put some blocks in front of the front wheels of course. I jacked it up, put the jackstands under the rubber jack point area, and lowered the car. I gave the car a good shaking, and it didn't budge, solid as a rock.
I then put the jack under the differential, and raised it until it was relieving a little pressure off the jackstands, but sharing the load. Again, I gave the car a good shaking to see if it was solid, and it did not budge, and was solid as a rock.
I proceeded to rock the wheels, lift up and down on them, and got a good feel for the fact that my suspension appears to be pretty solid, no play I could find really. Rubber all looked good.
Visual inspection showed it was dirty. Rear shocks had a bit of moisture on the lower shafts, probably leakign a bit, and ready for replacement soon, but car does not have excessive bounce, returns to normal pretty much as normal.
I did find that it appears my tires in the rear are getting bad, I will replace them soon, within the next couple of months. I will be able to get at least another 3-5k out of them if not more, but will replace them sooner.
All in all, pretty eventful day, I even got to mess around and tweak with my brothers range rover idle, as it was whacked all out, I returned it to factory settings, and smoothed it out from there, car seems good now... I hope.
I also removed my rear filler plate on the trunk, and buffed it up nice, also removed my trunk handle which has been painted, and stripped it, sanded it, and am priming it to give it a new fresh clean coat, it had some bad touch up work done to it. I found out the the real color fo my car is that mid greyish color, code 199, and my car has been painted, but its all good, I love the black paint I have.
SOOOOOOO..... Back to the point of all this..
I say make sure its solid on the jack stands, put the wheels under it, and keep the jack with some tension, and it should be fine.otherwise get 4 ramps, put the fron on the ramps, then jack up the rear, and it put it on rear ramps. with jackstands, and the jack all in place, it would be plenty safe I would think.