Blohm & Voss BV40-Bertha or how to bat-shit an already bat-shit idea
To the original BV40 project: in 1944, while Germany was perfecting its anti-bomber aircraft force, the allies perfected their bomber tactics. So soon it became apparent that if the bombers were operating in close formations, the defensive machine gun turrets of the combined force would cover each other and any attacking fighter would be expected to be hit at least once if not by the bomber he is attacking, then by one of the bombers flying next to it. And of course, flying a frontal attack, the part of the plane most expected to be hit was its engine.
So Blohm & Voss, a company known for constantly thinking outside the box decided to solve this problem by simply throwing out the engine so hitting it would not be a problem anymore. The resulting project BV.40 was in essence a pilot holding two heavy machine cannons encapsulated in stub-winged body armor falling more than sailing through a bomber formation, shooting at will at everything they can get their sights on while at the same time impervious to all enemy fire.
Makes sense... Somehow. Until you realize that in order to dive through a bomber formation the plane must get in top of it first.
Yet testing continued apparently to the designers' and the RLM's satisfaction. Until the BV40 got a victim of its own premise. While the plane was getting tested, Rheinmetal cannon builders took the idea a step further by not just eliminating the piston engine but also the pilot itself. The resulting R4m rocket ammunition was just that. A rocket that just like the BV.40 was launched from far away, would bust into the bomber formation without offering a target and explode, showering the bombers with shrapnel.... And it was dirt cheap, even compared to the already cheap BV.40
So the right thing to do was to shelve the BV.40 and arm the interceptor squadrons with racks of the new rockets under their wings. To their honor, this is exactly what the Luftwaffe did.
but if you want to go completely bat-shit....
then Goering or even the Führer himself would instead of scrapping the BV.40 order it to be equipped with the new R4M rockets and order Blohm-Voss and Rheinmetal to come up with some way of shooting it high enough to start their attack run.
the result would be about halfway between a Messerschmitt me.163 and a Bachem Natter, having the worst parts of both.