I would suggest starting with the addition of 3% butter or a high quality butter flavored margarine. No need to add any olive oil when adding the butter.
Salt has three functions in the dough. It controls the rate of dough fermentation (slows it down). Without any salt in the dough it would have a decided tendency to get very gassy very fast. Salt also affects the taste of the crust. With insufficient salt the finished crust will have a starchy taste. With too much salt the taste wil be salty. Typically, we see salt levels of around 1.5 to 1.75% of the flour weight used in pizza doughs. As for oil, the oil will contribute to a better, more appealing crust color. Since this color is a bit darker than that of crusts made without oil, or insufficient oil, if you bake a crust with oil and one without oil for the same length of time you will get a better bake on the crust with oil. This is what you are seeing with the crispier crust. Oil doesn’t give you a crispier crust, it just give you a better bake which results in a crispier crust.
Tom Lehmann/The Dough Doctor