Solution 1 is never a solution. One queue will work, the other will be dead day one. On top of it, I am certain as hell that my casual friends that do party up for FLs sometimes would just stop doing it and would go solo instead if it prevented them to end up in sweaty premade games.

Solution 2 doesn't solve the problem either, because it removes the possibility to queue with casual friends.

I do not understand why people insist in trying to split party play from solo play. Address job combos instead, notably pull ins, AoE stacking, etc.