Cavfab makes a spare delete plate that bolts up to existing holes but you have to add a brake light or combo license plate light. I got my combo light from Genright but then had to solve for the plate illumination power which doesn’t exist on the tailgate.
https://cavfab.com/products/spare-tire-delete-plate-tj-lj
https://cavfab.com/products/spare-tire-delete-plate-tj-lj