Ok, had a really bizzare idea.
1) run a normal club meeting. four rounds and a final with round by round qualifying.
2) At the beginning of the day. Drivers briefing. Draw teams of 4 out of the hat using seeded pots. So one from each F1/F2, F3, F4 & F5. Dependant on numbers. Some may want to opt out ;( or you could do a £1 in from each driver and the winning team gets a prize??
3) For the 4 rounds of qualifying (Ignore the final) add together the number of laps completed plus the time over 300s. So that way if Jonny F1, who qualified for the A on round by round, did 2 rounds of 13 laps, a 9 lap and a 2 lap. Total would be 37 laps + whatever extra time. that would then be added to the team score. Then Bob F5 newstarter did 4 rounds all of 10 laps. So that would be 40 laps to add to the team score. All team members added together for total laps and in the event of a tie the timings come into play.
That way every round would actually have a meaning on the team scores and (you would hope) people wouldn't just pull off if they were having a bad run. You can include 2wd, 4wd, sct, rallycross and even Roger
Not quite as manic as a 2.4 hour race but gives a bit of a different dimension to the day.
It may need a bit of admin but if you don't include finals in the overall team stuff there should be time to work it out.