I’m not assuming it’s easy, and I also assumed increased weight and drag, but missiles are frail, and another vulnerability of theirs is that they have a package designed to go boom.
many of them are going to terminal in on heat. Your anti missile device could target a narrow probability cone for any given one unit and fire flechette clusters or something along that line.
You know, when you think about it, a low tech force fielding a lot of prop aircraft could probably kick ass on a lot of current high tech forces, through numbers and creative means of getting the enemy to waste their very finite SAM capacity.
It’d be interesting to game it out...