Degree show work.
So the strip of wood or groove in the concrete floor were never going to work because they would be visible, which in turn would detract from the illusion I was trying to achieve.
Therefore, I tried my original plan of using hidden joints to secure the temporary wall in an angled position. I used strong metal brackets to attach the temporary wall to the existing wall and long screws with the plugs to drill the temporary wall deep into the concrete floor.
The result was my vision which seemed very secure at first, but on the fifth or sixth inspection was in fact not as secure as I imagined and was a health and safety hazzard.
I had to reconfigure this wall in a way that it fit within the space, alongside the three other walls I have employed as part of this experiential installation.
The wall now sits horrizontal against the floor, whilst being attached to the existing gallery wall in a way that it seems like it has either fallen into or is emerging out of the gallery wall.