Essentially, there’s really no evidence linking this image to the Miss Idaho competition. The best information that could be found is this theory: In the late 40s and early 50s, old school PR agencies for models and talent in beauty contests were using images of women with various fruit, vegetables or meat/protein products.
I’ve heard that too, but I couldn’t find any proof.
https://rare.us/rare-news/history/miss-idaho-potato-1935/