One of things I love about my mate is her breadth of experience and keen memory of details. I very much believe her when she relates a tale like this.
wulfwalker reports that the event occured in the early 70s and viewed in Charleston SC during an early afternoon children's programming block. Bozo came on after Romper Room. The studio set was small, only six high seats in the bleachers and about ten feet long. I could not find a possible match on the wikipedia site.