Thinking of the advice “healers should deal damage when not healing,” I wonder how you can be in melee range and still heal people behind you.
Paladins can heal people behind them.
If you mean Light of Dawn has a directional requirement, in general that’s not a concern because in a raid environment you generally just hit other melee players with Light of Dawn and facing the melee stack is generally pretty easy. If you need to hit a range stack, which is uncommon, you can generally position yourself to be able to turn temporarily to fire off the LoD and turn back around to continue melee. Remember though that LoD has a short range by default.
If you mean in mythic+, well, you don’t use Light of Dawn at all.
So much of our healing in raid right now is Holy Shock and Flash of Light. If you cannot hit enough people with LoD because of positioning requirements or, team spread, or whatever it might be, you should just use WoG instead. They do effectively the same amount of healing. In fact, I think the general advice is WoG unless it will overheal, then LoD.