option 1: drill and screw ply backing board onto wall then glue
the stainless steel skin onto the backing board ?

or

option 2: glue the stainless onto the backing board then glue the
whole lot to the emulsion painted wall ?

I prefer option one unless someone can assure me that the contact
adhesive won't have the paint off the wall. anyone have any experience
of the above ?

thanks in advance