Getting past the brick wall...

Hello! I am working on researching my great grandfather, Peter Olaf Rood and have hit the "brick wall". Peter reports he emigrated to the U.S. from Norway in 1900. He filed papers for Alien Registration in 1918, and I have a copy which I received from the Iron Range Research Center in Hibbing, MN. He reports on the application that he arrived in the US on May 20, 1900 with his port of entry into the U.S. as Stevens Point, Wisconsin. This doesn't make sense to me, as I believe he would have had to enter the U.S. somewhere else. He also reports on this two page application that he never filed for naturalization because he didn't remember the name of the boat or the first station he first entered. Peter never did file for naturalization as far as I can find. Peter reports his birth date as October 14, 1880 in "Little Hammer" Norway on this application. He reports the same birthdate on his World War I draft card in 1917-18, which also states he was being held in the County Jail in Duluth, MN. We think he was in jail because when he registered for the draft, he had not declared himself as an alien, thus prompting him to file the alien registration papers in 1918. Just our guess. Interesting enough, Peter was married at this time to my great grandmother, who was born here in Minnesota, but she also had to register as an alien because at that time if you married an alien you gave up your citizenship...at least that is what they told me at the history center. Peter ended up in Minneapolis, Minnesota and on June 23, 1903 married my great grandmother, Selma Ruth Anderson. They moved to Duluth where Peter was a tailor. I have censuses, etc. from his life here in Minnesota. He died on February 20, 1938 in Minneapolis. Where I am stuck is researching more about him in Norway. I have no information, nor does my mother, about Peter's parents, etc. the only clues I have about him are his birthdate and him reporting he was born in Little Hammer, or Lillehammer, I believe. I have searched on ancestry.com, the digital archives of Norway, parish books for Lillehammer and surrounding parishes in Oppland and come up empty. I have read about the naming system in Norway and realize his name may have been different in Norway. Peter does sometimes write his name as Peder Rud, Peter Ruud, but most the time uses Peter Olaf Rood. His wife took Rood, and his children go by Rood. Any suggestions or ideas to help me with my research? My parents and I are traveling to Scandinavia this summer, and would like to know more about his family and where they came from. Thank you for any help or suggestions! Nancy Anderson