I was trying to imagine what they might have tried to do with it. A larger version of the Marder III based on the PZKW III chassie might have worked? But those were being used in Strumgeschutz. III's which were doing good service. The Nashorns best protection was distance from things shooting at it. I had read an article saying that the optics on the Nashorn were good enough to score hits at 5000 yards. So stand off was the best method. If an AFV had to get in close it needed 80mm minimum on armour.
It was likely as you say the timing gave no real advantage. While the KwK 36 L/56 shells were about 7 inches shorter then the Panther's 75mm, I guess it would still have drawbacks in confined fighting compartments. Thanks for the input.