12v will definitely pump more light into the fiber strands; however, I usually use fiber for running lights, strobes, and spotlights. Great for a small, focused point of light but not as good for illuminating an entire cabin inside a ship, unless the space is very small. If it were me I'd forego the fiber and run a prewired LED (comes with a 12v resistor already attached) to each space. I've used these 0603 SMD LEDs for my builds and they are quite bright for their size. Lots of colors to choose from too. I'd go with the warm white myself. The wires are about as thin as a human hair and very so much easier than trying to bend .75 mm fiber:
https://hdamodelworx.com/0603-Resin-Encased-SMD_c_119.html
If you decide to stick with fiber you can use heat to bend the strands for tight corners. Just set your soldering iron to a low heat setting and bend the fiber over the round barrel of the soldering tip as it heats up. You can also bloom the end of the fiber with a BIC lighter to turn it into a tiny bulb shape for better light dispersal. I would also recommend a flat topped LED as your light source for the strands.