IMO, either 3rd baseman or Pitcher covers 3rd base when a runner is on first and the batter bunts. Which ever one doesn't field the bunt (3rd baseman covers if neither of them field the bunt). The pitcher, if she is 35 feet from home, then after her pitch, she is about 35 to 40' from 3rd base...
grass infields
A modified baseball diamond was used this June for an ASA National qualifier at Walt Disney World in Orlando. It was terrible. Bases put at 60' on a 90' basepath. Infielders played on grass, outfielders played on the baseball fields clay infield. An attempt at a clay circle...