So if it were teams, then there would be 1 car per team with 2 3 drivers?
Rules would have to change to allow different designs to re-allow refueling.
Then that would lead to a chassis re-design and you end up with what Nutritional has stated. LMP1 2 cars.
Really when motoracing all kicked off, long races were normal. As rules have changed by the differing organisations (ACO FIA etc…) we end up with LMS F1.
When the rule books were similar, between organisations, in the past you could enter a Grand Prix and Le Mans quite easily. But then you also had a riding mechanics, to help keep the cars going when they broke down.