Joopson and Benjammin thank you very much to both of you. I solved the problem. I combined the two (texture och translucency) nodes into one system. :)
My first instinct was to invert the normals on the tent, bake down a "lighting" map with a light in the midst of the tent, and use that as a base for an in-engine emissive. I think it has potential as a basis, especially if the vibe is what matters, as opposed to the physics of the light as you move around the tent, etc.…