I think your idea is great. Building on that idea while maintaining the imms stance of "no", here's a slight alternative:

Give players a choice to use a boosted experience credit each week that resets the same time cabalwars stats are.

Say you're on at 2 in the morning and can't find a group, you activate a 2 hour credit for the week. The boost goes away if you group people. If you log out, it will go away, but you can activate the rest later. Everyone gets only 2 hours per week. Also helps people that just want to spam skills.