I forgot about another route to living people who might have known David - Consuela's siblings. This might be Consuela in the 1940 census:
1940 Harlingen, Cameron, Texas Jesus G Torres24 born about 1916 in Mexico Berta G Torres24 born about 1916 in Mexico Consuelo T G Torres5 born about 1935 in Texas Conception G Torres3 b Texas Berta G Torres1 b Texas
Seeking the younger sister on Facebook, I find a woman with that first name, with middle name Graciela, followed by the name Torres and the name Reyes. Normally I don't post info on living people but she has posted her own name publicly (not private settings) so I hope it's okay.
Below are three relevant Ancestry.com databases (there may be more). To find them, choose Search, Card Catalog, and enter title or key word. Sometimes when you search just one database, you get better results than when doing a general search. You may already know and do all this - if so thanks for your patience.
Border Crossings: From Mexico to U.S. Mexico National Census U.S. City Directories
I kinda suspect I'm saying ideas you already thought of. I hope a family member finds you or vice versa. All best.