I used to shoot a similar drill with my 6 in round plate where I'd use the bolt hole inside the 6 in round instead of the 1 in tape sq again using the spray painted shadow. In the corners of ipsc home made. Also head boxes and a sharpie one inch ish square. These are harder for me since I have a full size steel plate that doesn't produce the head boxes. But I cut a chunk of scrap wood to make that.
I used to install water heaters regularly so big sheets of cardboard were a weekly thing.
I came up with some real estate sign holders made of angle and built them so the cardboard could drop in. They're about the size of a USPS box actually.
With pawnee being predictable weather the smaller surface area with a full frame would only get ripped down once in a while. The steel would usually stay up.