Just make a rule that says they must run 51% of the original race distance in competition (not behind safety car) for it to count. . If it's not safe to compete, let the teams vote if they cancel a race or run it later or on Monday. Michale Masi gets a tie-breaking vote, if that happens.
No race, no points. Move on.
As for visibility, they could put LED lights in the curbs to mark the track limits.