I never had good luck with creepers, running over cords and fingers, wheel dropping into expansion cracks, tools getting lost underneath them, not enough ground clearance etc. etc. So for the past 30 years I have used cardboard and carpeting. They now make "creepers" that are just a roll of soft rubber that supposedly scoot along but I haven't tried one. A roll of carpet or, in my case, I have huge pieces of carpet in my garage that I just park the whole vehicle on. Keeps the floor clean from spills too. In the construction trade we are always able to find new or slightly used carpet that is getting removed.
I also have a set of interlocking workout mats that work great too.
The cardboard is great too because you can easily slide on it, and it protects your floor.