According to wiki,things that improve RS are
1: Long races-the long time you race,more skill you get.
2: More opponents
3: Better finishing place
So META night race is to do docks and usual 100 laps are finished slightly below 5hrs
If I sleep for 7,does it make sense to join class B or even class C cars only,so whole race is gonna last 6-7 hours and with starting wait,im gonna fully gain xp for the night? Does it make sense,or class A cars give more XP that is not mentioned in wiki