Better solution for teleporting portals in unity

Up until now I’ve been using render textures to make portals for a project i’m working on, I was wondering if there is any better way to do this.

Been looking around the internet for a few days, but can’t seem to find anything other than using “stencil buffers”. I know how to use the stencil buffer, but I can’t seem to figure out how someone would make a portal using that.

Also by portal I mean similar to the game “Portal”, I would be using it to fake a room that is bigger on the inside.
For example: I would have a wall with a hole inside of it that has nothing behind it, but when you look into the portal it would be another room.

Another good example would be the game “antichamber”, they used something similar to make a looping hallway and stuff like that.

Define what you mean by “better”. Better in what regard? Manually rendering two cameras using a stencil window is tricky as you need a precise render order of the cameras. Apart from that you still have to setup a custom projection matrix (specifically an oblique near clipping plane). What are your exact problems using render textures?