Plus, most carriers aren't really that obsolete. Even condor has a role tbh... The only one currently I would consider being kinda weird is the Drover... But I've not given it much of a chance tbh.
Valid points there, though I did not mean that Condors, Moras or other carriers would be obsolete
in general. They are very detrimental to your fleet composition however when you want your carrier skills to focus on other carriers' fighter bays.
As it is you can use the skill for Shepherds, Tempests and base Ventures. If you go all the way in the tech skill tree to use an Apex with this hullmod then Ludd forgive you, because I most certainly won't. Same goes for Tempests, maybe even more so (the built-in wings being the same, but more essential for them I believe). That leaves a grand total of
two ships which are both applicable and a good candidate for the hullmod. In contrast, Converted Hangar can be added to anything bigger than a frigate and not already having fighter bays. No restrictions. Additionally you can add Converted Hangar while on the move, not needing a station to dock at. If either of them should require a dock to build in, it should be the other way around! At least per my understanding it would require way more effort to fit an "improvised flight deck", than to simply not use an existing flight deck and store stuff in it instead.
To look at it from a narrative perspective Condor carriers are basically "sawn-off" Tarsuses (Tarsi?), which are freighters. Moras, as mentioned, were demilitarized and used for "surveying, mining, construction, drone handling, and use
d as mobile drydocks". Gemini are cargo haulers with a fighter bay used originally for mining pods. It would make sense for these ships to be re-purposed again as freighters when needed by the ragtag polities of the Sector.
From a gameplay perspective, even the tooltip suggests that the hullmod was created with all carriers in mind: 20% crew reduction per removed fighter bay, maximum capped at 80% (4 bays). From the 4 ships you can use this hullmod on only the Apex has more than 1 bays, and it doesn't use crew space anyway. Furthermore, as fleet skills have a soft/flexible cap, it is important to be able to regulate the actual number of fighter bays you have, so that you get the most out of the skills you build up.
To sum up: my preferred version of the skill would work on all carriers, use the same bonuses it currently has and would not require a dock to build in.
Another idea would be to make it more the opposite of CH, decreasing the DP costs by 2 per Fighter bay removed, but that may be stretching it a bit too far. Alternatively that could be a separate militarized version of the hullmod.