...but also I couldn't see any references in them to actually build the TEC starbase in particular
From what I can see:-
FrigateTechStarBaseConstructor.entity -> ability:0 "AbilityDeployStarBaseTech"
AbilityDeployStarBaseTech.entity -> starBaseType "StarBaseTech" -> StarBaseTech.entity
Both FrigateTechStarBaseConstructor.entity and AbilityDeployStarBaseTech.entity have a prerequisite on the same tech, so your copies may need to change to reflect any new research you've added for your "starbase lite". Eg imagine the player researching your new starbase tech, but not the old one. Your constructor could be unlocked but the ability could still be disabled if that depended on the old tech. IIRC you also have to add new research to the faction's PlayerTech*.entity too.
I'm guessing your copy of AbilityDeployStarBaseTech.entity is using something like ...
starBaseType "OutpostTech" -> OutpostTech.entity
...to build your outpost