Having played the game for some years I've now pulled my active teams from all online leagues because I like to be able to compete for championships but know I can't because I have other real life commitments on certain days which prevent me from attending some races.
It's not really feasible to create leagues with non-race days to accommodate the RL activities of all players. So how about a championship points rule that can be set by the host where a limited number of results count towards the final championship table?
As an example, for a 20 race season, you might select the best 17 races count. A player could miss up to 3 races in the season without adversely affecting their title hopes and players who attend every race have the opportunity to discard their three worst results. (We've all had those brain fart moments... forgot to set up / forgot to renew engine / drivers not at full health / didn't set a practice lap / screwed up AS etc.)
I can see a few possible drawbacks, but this suggestion is for a host selectable rule, the default would be for all races to count.