Uhh, I didn't take that into account, so right now modular ships are pretty OP if you use it with the ship forge mod. I do plan on removing that option in the future, however, in case you want to make a fleet that you'll play long-term.
Well i have quite opposite feelings/expectations about this. Previously i played mining-fleet sessions, but it get's kinda booring, you don't even need to search for good gas giant outside core worlds because factions don't mind if you gonna mine resources in their home star systems. So you have no risks, just cource between few core systems, harvest volatiles, sell it for easy money. Thats mining at it's finest.
However, with your mod i see the opportunity to create fully selfsufficient fleet and mining gonna play important role here. I would call my faction Nomads for obvious reasons and probably gonna have only one colony somewhere on the edge of the map, just to make my faction "legit". Instead of creating outposts i would just remember planets with rich resource deposits, travel between them, sometimes make "pit-stops" beside gas giant to fill up fuel tanks. That's sounds amazing!
I really want to transform something like Cathedral from S/W pack in to real mobile station. It has 7 modules, so i probably can fit 3 supply forges and 3 smelteries while center piece would have antimatter cetrifuge, mostly for fuel economy buff. I assume it would work like efficiency overhaul - only hullmods from "core" module would affect "logistic" stats of your ship. Like max burn, cargo, fuel per light year etc.
But i am not sure about default rates, i still don't know yet how this works, i see limits of created commodities per day in settings.json and they doesn't look promising, so maybe i would have to tweak them to make this idea work, which mean what you no need to worry, you mod is not overpowered at all, it's just add more depth to mining. And don't fogret what ships with such expensive hullmods + mounts filled with mining equipment are totally non-combatants. So they have to maintain not only themselves, but also the guarding fleet.