In my view, the way to fix the Designate spell is basically to remove the second paragraph and change the Drain Code to (F/2)+1. That's +1 for a Physical spell, 0 for Line-of-Sight range, 0 for Sustained, 0 for Realistic, and 0 for Multi-Sense. You'd need to beat the OR of the targeting system to trick it into believing that there was really a designator shining there. Net hits would add to the attack roll.