I have another idea that likely won't be popular, but I think would be the most fair solution: Ration everyone's playtime. Temporarily implement a daily playtime limit of X hours, and enforce it at the service account level. The limit could be increased, then eventually removed as the surge dies down. This would help deter AFKers, as going AFK would still count against your limited playtime. They could also incentivise playing during off-peak hours (I.e. early morning) by giving you an extra hour or two of playtime that can only be used during off-peak hours.

To start, perhaps they could give you 3 normal hours (Can be used any time of the day), plus 2 off-peak hours (Can only be used during off-peak hours), for 5 hours total per day if you are willing and able to play during off-peak hours.