Your great-grandfather William Henry Everest does indeed appear in Winifred Lovering Holman's DESCENDANTS OF ANDREW EVEREST OF YORK, MAINE (1955). The main treatment for him is on p. 311 (I have inserted wives' names in the ancestral tracing):
"WILLIAM HENRY-8 EVEREST (Rev. Marshall Dudley7 & Martha Aull, William6 & Mina Holcomb, Capt. Zadock5 & 1st w. Sarah Moss, Benjamin4 & Esther Dudley, Benjamin3 & Hannah Jones, Isaac2 & Joanna ----, Andrew1 & Barbara ----), b. Northfield, Ohio 13 Oct. 1858, d. Sauk Rapids, Minn. 3 May *1955*; m. Crow Wing, Minn. 24 January 1887 LIBBIE* ALICE PHELPS, b. Pine Island, Minn. 16 January 1872, d. Brainerd, Minn. 9 April 1942, dau. of Eugene Marius and Mary Eliza (Flint) Phelps.
"As 'Willie,' aged one year, he was with his parents in 1860, in Macedonia, a village in Northfield, Ohio, and was taken by them as a young child to Crow Wing Co., Minn., where in the 1890s he is described as a merchant. Father and son took up adjacent homesteads there, of which a part was sold to a lumber company by William's second daughter, Mr. Everest was a schoolteacher, merchant, rural mail carrier, agent for farm machinery, and a Justice of the Peace; he also wrote articles for newspapers and was recently honored by Sauk Rapids, during its centennial, for being a pioneer there and its oldest living resident. Divorced about 1923, he was almost blind during his last years. He lived for some 13 years in Crow Wing, then in Brainerd and with his daughter in Sauk Rapids. "Judge" Everest had made a life-long study of the Everests and had gathered data on his own branch."
Children were [much more detail in Miss Holman's book, but there is only so much time to copy this]:
Ralph Marshall Everest, b. Crow Wing, Minn. 27 Oct. 1887 (= Elsie May Walker). Issue.
Mabelle Clark Everest, b. Crow Wing, Minn. 16 July 1889, living Brainerd, Minn. 1954 (= Peter Ole Petersen). Issue.
Nellie Gertrude Everest, b. Crow Wing, Minn. 9 January 1891, living Sauk Rapids 1954 (= Charles Henry Ackerson). Issue.
Charles Eugene Everest, b. Crow Wing, Minn. 4 April 1893, "family has not been able to locate him since World War I". No known issue.
William Dudley Everest, b. Crow Wing 23 Dec. 1895, d. Chicago 13 Aug. 1939 (= Hannah Matilda Nelson). No issue.
Cecil Sidney Everest, b. Crow Wing, Minn. 11 Dec. 1897, living Inkster, Mich. 1954 (= Della Matilda [Severson] Blackburn). No issue.
Morris Foster Bull Everest, b. Brainerd, Minn. 30 Nov. 1900, drowned Mississippi River 16 July 1917.
Ruth Alice Evelyn Everest, b. Brainerd, Minn. 9 Aug. 1904, living Sauk Rapids, Minn. 1954 (= Dewey Ackerson). Issue, about whom you know far more than I do: Calvin Jesse Ackerson, Cecil Dewey Ackerson, Gerald Elmer Ackerson, Gail Eileen Ackerson.
*Miss Holman's footnote: "'Libbie' is a diminutive for Elizabeth. Eugene Marius Phelps, b. 21 March 1847, Portland, Wisconsin, d. 19 March 1925, Brainerd, Minn.; his wife, b. 30 Oct. 1850, Yellow Springs, Ohio, d. 25 March 1932, Brainerd. Mr. Phelps was son of Aaron Gilbert Phelps, b. Waitsfield, Vermont, and Eliza W. (Foster) Phelps, who came from the East; they res. Lone Rock, Wisconsin, and settled in Minn. in the early 1870s. See 1899 Phelps genealogy, which is incorrectly indexed, at pp. 817, 1133."
Hope this helps. I'm your cousin through descent from Lieut. Benjamin Everest (1752-1843), brother of Capt. Zadock Everest (1744-1825), both of whom lived their adult lives in Addison, Vt.
Best wishes, Julie