I place all the film in one box. I used to do the N- and N+ thing but lately I take a fingernail clipper and cut a corner for N+ and two corners for N-. It works and I have not ever clipped into the image.
If I were Chrisl, I would not take the lgformat camera to Europe at the this time. I would just carry the smaller camera that I was familar with at this time. A trip like that is not something I would want to chance important images with uncertain technique. Just my 2 cents.