OP,
What is the mission of the aircraft?
Light ground support?
Air superiority?
Something like a Cessna Caravan could be used for extraction of wounded or ground support.
Small turbine aircraft are being sold to 3rd world dictatorships for ground support and suppression roles.
To “fight” a fighter with a light civilian aircraft and you’d need to catch them on the ramp or taxing with a weapon load.
That’s essentially a suicide mission.
A light machine gun on a light aircraft is not going to have the range to do anything or the ballistics. A shoulder fired missile strapped to the fuselage of a light twin will work…once.
My suggestion would be to use a Piper Seminole as they’re no good for anything else anyway
Honestly you’ll be better off using drones, weaponizing commercially available or home building simple one way attack drones like the Houthi rebels in Yemen are currently doing.
