License: This is licensed for non-commercial use only.
After more help in the Sketchup forum I have finally got the back part of the envelope to exported correctly via Sketchup as .obj.
I have tested the envelope model in Bryce and all sides now been textured. Please test the model and inform me if there are still issues. I am actually a beginner in all programs used. If there is interest I am planning to do more of these! :)
I have again used Guy91600 (got permission) clothing on the renders done in Daz Studio.