Well, Marlin goose guns can only reach so far so counters to drone tech will have to be found. We won't have a production facility churning out expendable electronics so producing surface to air missiles isn't likely, you can't count on capturing ordnance, so you need a drone.

...Except that the bad guys will have an AIR FORCE full of jet fighters explicitly designed and built to shoot down enemy jet fighters. Worse, they will have control of the electromagnetic spectrum; they can jam any control signal, even using spread spectrum technology so the drone will need to be fully automated. Fortunately, it doesn't take a Intel chip worth of computing power for a air to air missile. Airframe, sensors(I favor audio and optical recognition) can be had relatively easy or built. The engine will have to be simply constructed which rules out jet turbines-it will be rockets and ramjets.

Basically we need work arounds and the ability to adapt existing technology.