Here's another Idea, call it food for thought.
When the Nvram corruption happens, instead of doing ergn41 would it not be better to restore a generic region 41 (that already knows the model number of that nuvi)
I don't have the skills to create a generic region 41 for a particular Nuvi but I know that Such skills do exist.
When I have nothing to do maybe I'll stare at the Hex Editor some more.