The upside down jack stand on the floor jack doesn't stand a chance. There isn't anything keeping the stand centered on the jack with wheels on it. The top end of a jack stand is only about an inch wide, and then its not flat. You couldn't even put the stand on the jack and have it stay in place until you made contact with the vehicle. If there was ever a book on improper use of jack stands, this one should be at the top of the list.

At least with a 4x4 you have a 3 1/2" square base to center the load, and you get some warning when it tips. The 4x4 will at least stand up on the jack base as you jack it into place.

Its pretty obvious some here have no hands on experience working on cars or trucks.