For a real "Who's Who" of character actors, do a Google search on "Long Long Trailer movie cast."
You'll find Floyd the Barber from the Andy Griffith Show; Ma Kettle; Aunt Harriet from Batman / Larry's Mom from Leave it to Beaver; Keenan Wynn (full name Francis Xavier Aloysius James Jeremiah Keenan Wynn), with more Disney and other credits that you can count on both hands; and many more.
Keenan Wynn was the traffic cop. Many of the others were at the Trailer Court (I think that's the term) where Nic and Tacy went on their honeymoon, and which I'm still tying to locate for a rally.