I have seen plenty Voss that can fit at least 2 of the 4 body models in character creation, and if they ruled out the bulkier looks for the sake of adhering the closest to the way the NPCs look then that's cool. I would argue that when you play a Sith storyline as a Pureblood Sith and they talk down to you because you're not a Pureblood Sith, that's a pretty big conflict of the facts of your character to what the story is telling you. It already exists in the game as an exception, so let it happen with the Voss as well. As far as your character not knowing about Voss, that's simple enough to say you never grew up among your people or even on the planet. For any number of reasons you were taken in and raised by one of the two factions. It's also been said it would be weird to think of them as anything but Jedi, but the same could be said about Pureblood Sith as only Sith and you can play them as anything you want once you've unlocked them. Screw stereotypes. Besides, you have Main Character Armor, it protects against plot incongruities.