I for one don't want the cargo freighter magically becoming a tier 1 battlecruiser just because some junkrats ripped a few cargo containers out and threw on a few more guns. It's a freighter, not a ship of the line. It shouldn't even be in combat to begin with.
Ahh, the should-haves and the should-nots. I myself am by your definition a demonic junkrat because I have already thrown two drams into the Warp alongside with my rage and hatred and thus I now have a symmetrical Dramlord-class Doomsday Doomfire Freighter and not just a mere tanker anymore due to natural Warp-infused Timelord-esque storage units alongside one huge large weapon mount partially in a Timelord-esque storage unit that has one built-in Doombore cannon (8 Hellbores combined into one single rapid-fire super weapon) that are all fueled by sheer will, hatred and the rage of Khorne! MAIM! KILL! BURN! - MAIM!! KILL!! BURN!! - MAIM!!! KILL!!! BURN!!!
That aside I tried running a Diable fleet of my own in easy mode, didn't work out for me in easy mode either so I had to steamroll all of incoming hostiles into tiny particles with my super-ships. I hate restrictions, I hate challenges and I frelling hate humanity in general.
I personally don't see the point of playing a game without challenge. If I win by default why even waste my time with it?
Anyway, early game a close-range vapor wrecks basically every other frigate (and most destroyers/even some cruisers) handily.
Augmented engines
Aux thrusters
Insulated engines (whatever the mod that gives you greater engine resilience is called)
2x Trifire
2x magic box
As many vents as you can fit with the leftovers
Spec char for extended range/OP/and Flux venting
Don't use your shield--play it like a schmup and dodge fire to keep the Flux advantage. Once you learn to properly lead the Trifires for long range hits you will utterly dominate anything you'll run into for the first half of the game. Can easily win 1v5 situations.
Late game is all about stand off sniping while using wanzers to tear them apart efficiently.