Could it be a viable solution?
If the idea is to limit the amount of Champ Points you can get a day, why not make it like the Ultimate Gain?
Whenever you are doing damage, healing, etc, you get a buff, that increases the amoun of XP you have till you fill the champ point bar.
That way it would still be limited but people that would want to play 24/7 would still get more CP than people that would just rush to the CP cap/day.
Someone probably suggested that already, I think would be a nice solution.