You just illustrated my point despite yourself.
Reagan was constantly villified and belittled as a "B" grade actor (Death Valley Days, Bedtime for Bonzo) even though it'd been more than a decade since he had filmed them.
So the attacks have and will and do go further back in the past than just ("late-70s to 1980") or the equivalent for Palin.
But -- despite the ubiquity of the attacks -- they rolled off.
People wanted America to succeed after Carter: and when Reagan's policies worked, the people said, "BFD!" to the affected criticism.
Cheers!
But, he appeared in those movies BEFORE he got into politics. He would have, justifiably, been viewed as a joke of candidate if he had been doing that in the 1970s before running for President.
Appearances by Ronald Reagan in the 1970s on television according to the IMDB which could be consideted less than serious.
1970 The Carol Burnett Show.
1972 The Sonny and Cher Comedy Hour
1973, 1974, 1977 The Dean Martin Celebrity Roasts. In 1973 Reagan was the one roasted.