There's a mod on steam workshop which adds in many custom roles. A fun round incorporating those would be interesting, since it could actually be a full-fledged round, and more players could have special roles at once than in modes like hidden/reapers. I don't know anything about how putting that in would work, but maybe points could be based on which team wins? the mod adds in groups besides just innos and traitors so it'd wouldn't be as straightforward.