i thing the best way is AMB owner (me also) charge a fix rate per race per day. so the wear and tear will justified with the rental.
and organiser can budget their cost even few racer turn out.
e.g. RM5 per racer so for 1 day race 50 turn up RM250 for AMB, 100 racer RM500 so on
i'm sure no one want to race using stopwatch, paper and pen as their timming system right