Axle stands tend to have tripod bases. Make sure that the bases are not aligned. It is easier to topple if two bases at one end are in line. And when you lift the second end watch the two stands closely in case they rotate.
I made my wooden blocks to be safer than stands. Step 1 is up on the side of the blocks - one end at a time. Step 2 is on top of the blocks. This is totally stable. Then I remove wheels if necessary by jacking as normal and adding an axle stand if I need to go underneath. I can also use the blocks each end of the jacking beam for a lower lift.
