The interior of the sub is called from the cfg file, so that would mean needing a new submarine class to change the interior. That is a major problem with the game, in that going from one class of sub to the next, without fail, would entail the player being in-port at the time of the change, and that there would be no other boat available, else you have a failure of either no "upgrade", or an upgrade to the wrong boat.
The covers are in the sensors.dat file
and most of the boats' CT interiors are like this:
The problem is that they seemingly do not operate independently. I do seem to remember a post or two from someone (you Nisgeis??) where they were experimenting with these, and had several issues that I do not recall the details of. It is so tantalizing to try some experiments though, because there is this:
[UserPlayerUnit 1.Compartment 4.EquipmentSlot 4]
ID= EqSlot42
NameDisplayable= A-Scope Radar Cabinet
Type=NULL
AcceptedTypes=NULL
UserCustomizable=No
IDLinkEquipmentIntervalDefault1= NULL, NULL, NULL
ExternalNodeName3D= NULL
ExternalDamageZoneTypeID3D= -1
[UserPlayerUnit 1.Compartment 4.EquipmentSlot 5]
ID= EqSlot43
NameDisplayable= PPI Radar Cabinet
Type=NULL
AcceptedTypes=NULL
UserCustomizable=No
IDLinkEquipmentIntervalDefault1= NULL, NULL, NULL
ExternalNodeName3D= NULL
ExternalDamageZoneTypeID3D= -1
in the SubName.upc file, which would insinuate you could have them "active" at different times, but like the Observation Periscope versus the Radar Periscope, experiments have proven otherwise, like they are joined at the hip, and seemingly are not allowed to "update" to a new state of activity... The consoles are listed in the sub hull, along with the air search radar, while the surface search is in the conning tower UnitParts file. All are updated in the SubName.upc UpgradePackSlots section... just slightly confusing.
So... there are several conns in the Objects folder for each sub... Is it possible maybe, to have several "hulls" in the SubName folder, and then use "UnitPart 1" and "UnitPart 2" to call gear???