Hi Sarah,
Yeah I guess mime file is the way to go.
Goto SE80 -> Click on MIME Repository -> goto SAP/BC/BSP/SAP/<YourUI5ApplicationName>Context Menu -> Import Mime Objects ->Select your json file to Import
Now goto /sap/bc/bsp/sap/<newfolder>/<YourUI5ApplicationName>/<yourfile> in your browser.
Regards
Krishna