I think we need to go WAAAAY back
Was Dan Quayle as light-weight as Sarah Palin? Actually, no. Dan Quayle's experience in the U.S. Senate lasted eight years. That's not terrible. I've watched some of his debaes. Hardly astounding, but he sometimes more rational than his fellow Republicans.
Some quick web research shows that R. Sargent Shriver was the last time anyone was chosen for VP with this little heft. Shriver was chosen by McGovern after McGovern's first pick, Thomas Eagleton, was found to have mental problems. Shriver had held no elected office, had served from 1941-45 in WWII as a Lieutenant, was the first director of the Peace Corps and an Ambassador to France.
This map shows how it turned out in 1972.
P.S. How do you serve more than four years in WWII and end up a Lieutenant?