I have a couple of the old quilted type moving blankets that I use when not opening things up.
A layer or two of cardboard bent to fit over the fender with the blanket over and under is nice.
I never lay tools on the cover as in the pic. Rather, I use a small roll-around cart, and for small jobs one of those magnet backed bowls on the fender ledge, or radiator support, On nice paint I use a clean shop rag under it.