Early Stanislaus Records - the marriages Mrs. Ray Dix of the DAR typed; History of Stanislaus County; Stanislaus County Cemeteries; History of San Joaquin Valley; Illustrated History of Sacramento COunty;
all in the Special collections room at the Modesto branch of the Stanislaus County Free Library. I couldn't find any mention of your Wilsons.
I'm posting this as a reminder to myself. Another researcher may know of more places to check. Sorry.
William and Elizabeth's marriage is on the IGI, and two people have them and the kids on the PRF over at LDS Central,