You're definitely getting ripped off. A good dealer makes all the difference in the world. I do my own tire rotations every 5K, but bring it in to Morande Ford in Berlin, CT for the 10K oil changes. The service has been very inexpensive and the staff has always been very helpful. I think you should name the good and bad dealers to help other owners.
I can't imagine MN as a severe environment any more than New England. Three feet of snow? Check. Freezing rain? Check. Potholes, traffic, random road debris? Check. Wild temperature swings? You bet. Severe service generally means you shorten the air filter change interval and do more frequent oil changes. The transmission fluid should not be affected or replaced earlier unless the vehicle is used for a lot of towing.
I'm glad you had the fortitude to walk away from that stealership!
