Bill,
I could be wrong, so I recommend calling the factory to confirm. However, I think that if you Google "trailmanor factory, sd," the map that comes up on the right shows the map of the factory, which appears to be on the south side of Mitchell, off of route 11. Also, I think this is correct, because it is by OES Industries, which is where I think they get their aluminum.
https://www.google.com/maps/place/Tr...!4d-97.7934403
We're actually going to South Dakota this summer for a vacation (cabin rentals, though...not with the TM). Since we may go through Mitchell, we are thinking about an excursion to the factory just for fun, which is why I had been looking at the map. If you gain better insight on their location, please share.
John