Seeing that no PD on a Lasher with no omni shield is a bad idea, I looked for another configuration that could work, and did so. I can still destroy a Hegemony defense fleet with four Lashers.
Lasher
Weapons: Light Needler, Light Assault Gun x2, Light Machine Gun x2, Harpoon SRM (Single) x2
Hullmods: Augmented Engines, Expanded Magazines, Front Shield Emitter, Hardened Subsystems, Integrated Targeting Unit, Resistant Flux Conduits
Capacitors: 11
Vents: 10
Light Assault Guns in hardpoints for anti-armor, Light Needler at the front for anti-shield or general purpose assault, and Light Machine Guns at the rear for either point defense or melee attacks. Vulcan is better than Light Machine Gun for missile defense or finishing off unarmored ships, but it spews ammo too quickly and wastes some, and cannot break shields like machine guns. Vulcans also have less range than Machine Guns.
Against the defense fleet, Light Assault Guns stripped armor. Afterwards, if my machine gun ammo was high, I would approach a target and fire machine guns to damage exposed hull.
Compared to my earlier Railgun x2 and Light Assault Gun x3 configuration, I did not waste as much ammo or overload as much. However, with machine guns, I needed to get close to targets at times to hit them with machine gun fire. Better to use machine guns when possible and save longer ranged ammo when it is too dangerous to stay close to an enemy.