Dude, hope the back end is up on more than jackstands. Almost had a car fall on me once from using 4 jackstands. A set of wheels under the rear tires makes it very stable. Just an FYI. If you don't believe me, try pushing on the side of the car and see how easy it is to get it rocking.

It depends on the placement of the jacks. I typically set the back ones at an angle. I had no issues of wiggle or fear of it falling.