I’m suffering with the same problem
I have already tried to build by connecting actors and build as components of one actor, and in both cases it turns out to be somewhat awkward and slow crap
I have some ideas but I don’t know how to implement them
paid attention, among other things, to the form in which ship drawings are stored in Avorion (this may be just the answer to the question of how to store)
if you need to build in the likeness of how it is implemented in TerraTech, then a good plugin came out with suitable functionality Modular Building System in Blueprints - UE Marketplace
maybe something will work out for you, good luck