I do agree , use marker mode , each marker at max 8 cm distance keeping at least 3-4 all the time in the FOV , and fir the size use Body mode with proper distance .
Unfortunately I cannot use markers on the surface.
Scanning sub might be an option. For these particularly objects, I’m looking to avoid any sort of use of adhesives that could damage the surface and looking for an non-invasive approach.
Markers are stickers , if you don’t press in too much it is so easy to remove it after , I did that countless times on many surfaces .
Set Range in Body mode , keep proper distance and try to scan a small section at a time , one by one then merge it together after .
Looking at that picture , it should be not big issue .
General mode request the scanner to be closer, how closer you get how more features you need , try Body mode , as it will give you the proper range for this size . You can place different objects around the sign and later remove it easily. It will helps to keep the tracking .