Yes, you can add JSON structured data to the body of your pages - Search Engine Land

JSON structured data can be inserted in the head as well as the body of your pages, Webmaster Trends Analyst John Mueller explained on the September 11 edition of #AskGoogleWebmasters. "Is it possible to insert JSON structured data at the bottom of the body instead of the head? It seems to work fine for many websites," asked user @largow via Twitter. Yes, you can insert JSON structured data either in the body or the head. Mueller also took this opportunity to explain the three structured data formats that Google supports. Rich results aren't going anywhere, so it's on SEOs to adapt their efforts to the search results page.