Received reply from Bonner County Museum regarding looking for Eric Mattson listings in Sandpoint, Idaho City Directories between 1920 & 1924. They do not have directories from 1917-1922. No listing was seen for Eric Mattson in the 1916 or 1923 directories.
So I did get an answer at least for the 1923 directory. Would still wonder about 1920-22.
I believe he was in Coeur D'Alene as of 1924.