Creating a room that is bigger on the inside

Hi all,
I've been working on a project recently and ran into an issue that I've just been putting off for weeks now. The effect I'm trying to accomplish is a room that's bigger on the inside, similar to this video of someone's work in UDK:

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The way I'm trying to approach the problem, is by setting up two boxes with trigger colliders that will move the player to the other box's position. For the time being, I've just set them up with a transparent material over them so you don't notice it. But it's coming to a point at which I think it is necessary for this effect to be present. Do any of you have any idea of how one could accomplish this effect in Unity 4.6 (free version, so no render textures)?
I just need it to be a convincing illusion, and it doesn't matter if it jumps slightly when you enter or leave the room. I also don't care about dropping frames, as I'm going to stop the effect if the player leaves the door trigger area, so they can leave the area at a reasonable frame rate.

Thanks in advance!

 

Have you looked at perhaps using one of the many "portal" clones? Here's one for Unity Free that I found:

http://algoholic.eu/unity3d-indie-free-portal-effect-project-sources/

 

Indeed I have, and I found that same example and thought it looked perfect for what I am wanting. However, that system is very poorly explained on his website, so I couldn't figure out how to create that effect, ever with his example project. I may have another crack at it now to see what I can achieve.
I found a method that works really well with the render to texture sort of situation needed, however it can only be used for the main camera in the scene onto a material, so you get all the GUI on the material, and you can't look at it without it turning into a never ending tunnel.
I'll come back if I have any success.
Thanks.

 

If you're still looking, I'd be happy to throw a way to get render textures with unity free onto this topic. It's rather slow compared to the real thing, but it does work. I'd love to see the math behind how the camera angles work and such myself, but I've only used this to make mirrors.