Besides being a fantastic small multi role and a not bad explorer ship - Mark IV is a solid combat ship, but requires solid engineer approach. Thing worth nothing, one federal squadron flies mk4's exclusively, they used to harass Cubeo some thime ago (google "elite viper blockade of cubeo" for materials)
Nevertheless... Pros - hull, hull, hull. Internals good for multirole, decent jump range, good hardpoint placement, not bad shield with perspectives for tanking.
Here is my shieldless brawler. Force shells + rails, fun in pvp. Without mrp hull goes up to 4000 which is INSANE for a small ship. I decided for single mrp, it gives extra toughness for weapons, because weapon systems are most prone to take damage in MK4 and especially small those small hardpoints, mediums are usually safe due to being positioned on the belly side. If you want that 4000 hull points simply dump the mrp and engineer your weapons towards sturdy and it is not that bad as weapons get extra piercing damage plus lowered heat production which is invaluable in silent running.
https://s.orbis.zone/6jj6
Another of my propositions comes with an enhanced shield. Good for a haz res fun. Just slap any weapons and have a blast. Acceptable recharge rates and SCB in case you need a quick boost. Tough enough to survive pvp interdiction and hi waking.
https://s.orbis.zone/6jjn