One stop kind of kills the 3rd driver concept. It then eliminates those that don't want to drive more than an hour from the field. [/b]
Not necessarily, if there aren't minimum times on the stops, and it also depends on the fuel capacity of the car in question.

Looked at the other way, mandating two stops kinda makes it three races in a row...which is NOT an enduro. It also "rewards" a team that wants to throw fresh tires at the car twice, as they now have no time penalty for doing so. Three sprint races with little tire conservation concerns results.

Open the stops requirement, and strategy options open up.

Back off the pace and conserve tires, but save a stop? Or go all out, burn down the tires and stop often? Choices, choices.

3 hours is also very makeable for one driver.