So far, anyway. Built three eighths of a 32 x 32 base plate and managed to fasten it to the pilaster beside my front door.

Four of the velcro type wall click-ons will together ‘carry’ four and a half kilos but I’m more worried about the Lego, This little scene is clicked to the blue background with three plates, all with between 8 to ten studs. Hopefully it will stay up. I’ll know tomorrow morning.
And then there are the four stud wide horizontals anchored only by a single row of studs at their inner edge. Have so far not weighed them down with too much, this is a test piece, after all.
If anything will give up, I’m betting on the base plate. They are such weak bits of plastic. I know, I know … I’m making this one do stuff it’s not designed for.
Using the third of my MILS plate designs did not work, scenes just too hard to install vertcally. I ended up having to take the whole base plate off the wall, and lay it flat, click the scene on, and re-join the velcro.