The easiest solution I can think of would be to give them a maximum distance they're willing to follow you from home and a decent-but-not-explorer-grade jump range. Similar to how you can't take an apex more than 100ly, NPC wingmen would leave the wing and end the contract there if you go too far from their home base.This will be complex for sure since you can technically hire a wing npc and take them to the black. If you make it system only, then they really become even less helpful.
Problem is that Frontier already kind of insinuated with Ship interiors that they won't work on something if it's too complicated.
I guess one may think of module reinforcement as a backup for most sensitive parts of your modules to be replaced/activated when main module receives significant damage.You wouldn't take them into the black - they'd be like 'dude what're we doing out here, screw this I'm outta here' and quit the wing.
Well this is different. It's just coding behind the scenes. The problem with ship interiors isn't that it's just a lot of work, it's fundamentally nonsensical. In a real spaceship you'd have a cargo hold, with spaces to put cargo. But in ED you can replace a cargo hold with hull armour, that goes on the outside of your ship? How does that work? And I am pretty sure that the outsides of the ships are not designed with the internals in mind. So ships would have certain slots on paper but you wouldn't be able to draw them. There is much that makes no sense. Module protection in place of a cargo hold? What? And how does a docking computer take up the same space as a tonne of cargo?
There are only two solutions to this:
1) Get rid of all the ships and start again
2) Come up with a load of arcane 'type homologation' style rules like we have for cars where certain combinations aren't approved, so having hull armour means you break some other rule about cargo loading so it's prohibited even though there's space.