I staple-gunned half-inch hardware cloth to some scrap 1x2s years ago and used it as a sieve over the wheelbarrow. Large stuff (at that time, Bermuda grass roots) stayed on top of the sieve; dirt fell through and was returned to the soil.
Purchase the hardware cloth so that it will keep out the size of rocks you want to keep out. A few pieces of pea gravel don't hurt the soil or you, but too many become a complete pain.
Make sure the sieve will cover the wheelbarrow, and don't overload it at one time, because you'll be lifting it with the "rejected" rocks to move them somewhere else.
Sunset Zone 17, USDA Zone 9