It's very simple chaps. If you've matched what's in the game; consider that canon. If you matched a figure, you need to look up the 501st's policy on what you can base your costume on for clearance.
For example, Mr. No-Stripes is a clearable and troopable Stormtrooper variant. He appeared in the film. Was it a mistake? Most likely, but it's there, on film and acceptable. You may have to argue the point with some, but your reference material is clear.
The reference material that matters here is the game.