I've done "shoot the negative on light box" method. It works with few caveats.
If you process normally, the resulting reversed negative is low in contrast. I guess you could extend the development time to compensate for it. Another is, it's awfully hard to get the alignment just right since not all view finders are 100% and accurate corner-to-corner.
I did this to make a print that is reversed. Because of this, I was able to compensate for all the problems at print time. If you are going to project it using a projector, it may not be the best method.