Consider changing the points system, so that only, let's say 7 out of eight, counts. This way
1) you wouldn't have to necesasarily take part in all races. You're allowed to have a life. Though it is highly unlikely, that a lfs racer has one.
2) you could get a way with a retirement. This would be fair since, this beeing a dangerous league there are all kinds of rescue cars on track.
Then, it should be mandatory to take part in practise/test sessions. Let's say off-season (or mid-season brake) tests too, with people practising together. But not with very strick participation perceents or anything, people are entiltled to have a.... nah, there won't be anyone who's got a life for starters.
Furthermore, I have one cunning plan which I doubt anyone will understand or like: Divide contenders in teams. Not because of a team championship, but because in a team there is a team leader responsible of the drivers. This hasn't been a problem this season, because all drivers I've raced against have been really focused on their driving, but this kind of an arrangement would make sure no-one comes without any practise to a difficult track and ruines everyones race.
Lastly, more race control. Deko did a fantastic job, nut one man can't watch everyone. Why not get a few more people to oversee things, to be referees.
EDIT: noticed a typo, but it's better off wihtout editing