I will provide a bit more detail, but it is Lactose! said.
1. Make a new Render Texture in the project folder.
2. Make a material, probably something either with an emission texture, or for texting purposes use the Unlit/Texture shader.
3. Drag the Render Texture into the texture of the material.
4. Make your plane(or if you already have UVmapped geometry) with that material, so you can see the render texture.
5. Make another camera, pointing wherever you want it to. Take the AudioListener component off of the camera so you don't get errors.
6. On that new camera, drag the Render Texture onto the "Target Texture" of the camera.
That is all I did, took less than a minute in my project to just add it in really quickly. It even works and updates in the editor too.