[APKhaos]

Here's how the overlapped group rollon/rolloff [RORO] works under NASA.

On the checker lap, the first and following cars in the returning group are vectored through the hot pit and into the paddock until the last car in the group passes T5.

At that point, the returning group is held in the hot pit and the new group is sent out under double yellow. When the 'ready' cars of the new group are on track, stragglers are held until the remaining cars from the old group are marshalled into the paddock.

In the higher run groups, the track goes green when the last returning car is through the hot pit. In lower groups, the track stays under double yellow for the first lap. Its that simple.

We can learn from this, given that its a proven procedure. No need to reinvent that particular wheel.