'Rock pegs' as some call them are fine in grass if you put them in at an angle rather than straight down. Angle the peg so that that the point is towards the point of load e.g. the tiedown ring on the awnings, or inwards if you are pegging doen the skirt. Get a good angle towards 45 degrees.
(Isn't it difficult to describe something you've done hundreds of times without thinking too much about it ?)