There is ony one William D McDonald born in Inverenss in 1898, and he is William Douglas McDonald. And this leads to this man who served in the Navy and was a motor mechanic, and I think that this is our man
1898 May 16. Born Inverness
1920 Nov 2 enlisted with RIC no 75185 ex-Sailor & Motor Engineer
1921 Jan 11. Resigned to maintain his health