Add a tracing image (background image) to a spreadsheet

I would like to add an image, as a 'tracing image', behind a range of spreadsheet cells.

I find that I can add a 'background image' (which, most puzzling, is not in the background but is on top of the cells so that the underlying cells cannot be accessed). I also see that I can add a 'wallpaper image' that is truly behind the cells, but that doesn't appear to be able to be sized or repositioned or to have the tiling feature turned off.

Is there a way to place an image onto a sheet, change its size and location placement (& transparency), and then "Send to Back" so that values can be entered into the cells that are in front of the image?

Thanks!