I think I might have your answer, hopefully you've found a solution since it's been several months, but this might help you and other users with the same question.
I did a web search for "code to create a hover-image" and this site came up:
I inserted a code block where I wanted the image, and then typed in the code. I didn't need any additional code, the block took on the shape of my image. It worked perfectly for me, hopefully it will help you as well.