To anyone having trouble with decals on the cargo containers, the issue is a missing ! on lines 12 and 13 of SSPXR-Containers-Switches.cfg. Kudos to @theJesuit for figuring that out—I certainly wouldn't have been able to on my own.
I wrote a ModuleManager patch that fixes it. Save this as a cfg and throw it somewhere in GameData to get decals back.
//fixing error in StationPartsExpansionRedux/Patches/SSPXR-Containers-Switches.cfg
@PART[sspx-cargo-container*,sspx-logistics*]:AFTER[StationPartsExpansionRedux]
{
@MODULE[ModuleB9DisableTransform]
{
//remove disable-transform if MKS present
!transform[#ExoticMineralsDecal]:NEEDS[MKS]
!transform[#RareMetalsDecal]:NEEDS[MKS]
//add disable-transform if MKS not present
transform:NEEDS[!MKS] = ExoticMineralsDecal
transform:NEEDS[!MKS] = RareMetalsDecal
}
}
I also figured out how to add inventories to ModuleB9PartSwitch subtypes, if anyone's interested: