For my floor jack , I have a pad like this to use under the pinch weld


https://cimg5.ibsrv.net/gimg/www.che...26dd04655.jpeg
It stops my jack from sliding around

I have 2 hockey pucks glued together so the lift gets the car up high enough for jack stands. In the US you can get a bag of them for $10, probably cheaper in Canada.
I don't worry about the slots for the pinch welds, I guess they are soft enough.