[RAF_Loke]

With the B-25J cockpit only, you're a sitting duck waiting to be shoot down... :?

True enough mate, but that was the case for C-47 pilots.
Take the Bomber Mossie, no guns like the C-47 a sitting duck too.
That is why you need good escort pilots, that don't run away just for a kill, but stays to keep your six clear.