I was ignorant and didn't remember to attach some slate to the bottom of the wood. So it's weighted down with various rocks until I yank it out during the water change tomorrow.
Couple rough photos after setting things up:
Likely adding a bit more moss and probably hiding some attached to lava rock behind the stump.
Have an Anubias nana 'petite' or two to toss in when I figure out where they belong.
Should probably add a bit more Aquasoil during the water change.