Just did a 5-lapper against the AI, the Vette was chewing up about 8% of the front tires per lap, and 16% of its fuel tank, lapping around 4 minutes, plus or minus a second or two.

The race starts at 3 pm local time, the sun sets around 10 pm, then rises again at 6 am, and then the race finishes at 3 pm. Let's aim for 1/10th the race distance, so 42 minutes, 48 minutes and 54 minutes. Since we want to include rain, we can stick that between the night and next day session, eat up 6 minutes of both (from my experience, 12 minutes of swimming at LeMans will be more than enough). Rounding for 4-4:15 minute lap times:

10 laps day (1 stop)
10 laps night (1 stop)
3 laps rain (0 stops)
12 laps day (2 stops)

What works better for people, 3+ hours on one day/evening? Two separate days in the same week? Weekend?

Do we even have enough interested people to make this worthwhile? I think that's the far more important question, and I think the answer is no.