You could try and find photos and stories about this team in the San Francisco Chronicle, but that would probably be fruitless. World War II was going on and that dominated the news in 1943. The San Francisco Bay Packers were a lousy team in a minor league and there is a very good chance that the Chronicle would ignore them entirely.
A better source would be "Best in the West: The Rise and Fall of the Pacific Coast Football League" by Bob Gill. In 2005, this soft cover book was offered for ten dollars by the Professional Football Researchers Association. However, their current website does not show that book being available. http://www.profootballresearchers.com
A third avenue of attack would be Bob Gill and Tod Maher's coffee table book "Outsiders: Minor League and Independent Football: 1923-1950." This book is available for $41.70 on Amazon.com, but I would inquire if this book has any information about the San Francisco Bay Packers, before buying it. Bob Gill did write about the Pacific Coast Professional Football League and I have read his articles about the Los Angeles Bulldogs, in old issues of the "Coffin Corner" which is the newsletter of the Professional Football Researchers Association. However, I have not read his more recent "Outsiders" book. I would hate to see you spend $41.70 for a book that ignores the football team you are interested in. However, if anybody has written anything about them, it is probably Bob Gill (the football writer) Be careful, there is also a rather prolific graphic designer with the name Bob Gill, and that Bob Gill has nothing to do with minor league football teams.