There are more ways to get it done with the Houdini stack, but I was able to make it work with Teleporter in the Forward theme, @davidfreels and @signfarm.
@pigglypots it really is a theme-specific hack because each dev uses a different architecture/design for creating a theme, for a variety of reasons. If the theme doesn’t like it, you’d need to either declare a custom CSS class using the CSS Box stack or figure out which divs are in the header and prepend or postpend from one of them.
This is on a blank stacks page with only the Teleporter stack and my logo. The declaration from Teleporter is set at “TeleportMe” and in the site setup title I put “TeleportMe”
If you’d like the image, text, and a nice break, you could do this: “TeleportMe < b r > Hello!” (no space for the br declaration).