Margaret McWithey m. Linn Homer Rist -- or did she?

I can't place her and I can't make sense of the records. It all started when I was fishing for McWithey entries at genealogybank.com and found this record:

"Miss Margaret McWithey and L.H. Rist were happily united in marriage Wednesday evening at the home of Mr. and Mrs. E.H. Conroy, the ceremony being performed by Rev.L.K. Grimes, pastor of the Hammond Avenue Presbyterian church. The following day Mr. and Mrs. Rist left for their future home on Mr. Rist's large farm in North Dakota. The bride has resided here several months."

-- Duluth Times Tribune 3-15-1908 p. 10

But I couldn't find a Margaret McWithey in my database whom I thought a likely candidate. I went to the 1910 census to pick up more information. I couldn't find a Margaret Rist, but searching RIST in North Dakota, I find a Linn H. Rist in Devils Lake, Ramsey Co., North Dakota. According to that census, he is 28 or 29 (I couldn't distinguish) married once, married 3 years ago, born Illinois, parents b. Illinois. He is a teamster in the draying business and rents. His wife is named Mary L. age 33, married once, married 3 years ago, b. Wisconsin father b. Ireland mother b. Massachusetts.

Using records on Ancestry.com, I can follow this family out... in 1920 they are in Gladstone, Hill County Montana; his age is given as 36, hers as 46. This record indicates his parents born Pennsylvania/Ohio, but once again birthplaces for her parents are Ireland/Massachusetts. Her name appears to be written Mary E.

In 1930 they are in Shelby, Toole Co. Montana. His age is 46, hers 56, they own their home, his occupation is common laborer and the birth places of parents match those given in 1920. The age at first marriage is given as 24 for him and 18 for her, indicating that her first marriage was not to him, which is contrary to the "Miss" designation in the newspaper notice and the one marriage designation in 1910.

The Montana Death index shows the death of Linn Rist in 1961, age 61 Roosevelt, Roosevelt Co., but this places his birth at 1900 rather than the 1881-1884 as indicated by the census. There is a death record for a Mary Rist, but that in 1946 age 77 -- indicating a birthdate of 1869 rather than 1874-77 as indicated by the census records.

I suppose I should get those death records to see what I learn, but I think first I'll try to get their marriage record, which I'll have to order from the courthouse. Am I chasing the wrong L.H. Rist?