You can tick the "Visible" checkbox in the Main Camera's Properties panel and change its display mode to something like Smooth Shaded. If you do that while you're actively viewing through the Aux camera, you'll see the main camera appear. That will let you know if you've placed the camera outside a wall or whatever. (We've all done it!)

As for backfacing polys, you probably have "remove backfacing polys" turned on for preview but off for on for your final render settings. That's why you can't tell your camera is just outside a wall. If the wall is made up of single-sided polys, then "removing" them means you can't see them from their back side, only from their front side. That's handy in preview for being able to see inside an enclosed room while posing, but not so useful for a final render if the camera is outside the room.

You can turn on "remove backfacing polys" in the Firefly settings (not sure about Superfly), and then the render will look more like the preview, but the downside is that items made of single-sided polys, like hair and plants, will look kinda thin b/c they depend on backfaces being visible to the camera. So that's probably not the best solution.

Another solution is to get the camera angle you want while the camera remains positioned INSIDE the room, and you can do that by adjusting the Focal parameter and/or the Perspective dial. 

Hope that helps!

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TOOLS: MacBook Pro; Poser Pro 11; Cheetah3D; Photoshop CC

FIGURES: S-16 (improved V4 by Karina), M4, K4, Mavka, Toons, and Nursoda's people

GOALS: Stylized and non-photorealistic renders in various fantasy styles