I would not suggest buying an undecorated one and decorating it yourself. Here it is just not worth it. All of the waffle indentations would be a pain in the butt to decal around. Stick with the stock ones, they are good as is.
Below are some of my waffle sided boxcars. Some
details you may want to add to be more prototypical are consolidated stencils.
I added one to the bottom right pic, but not the others. I did the
bottom left one with a blue overspray around the roof, this makes it look
more prototypical for a repainted boxcar. The painters aren't worried
about getting any extra blue on the roof. The top right one is actually
a #486143 that I overpainted some of the "4" with blue to make it #486113.
Since the C&O class goes from #486000-486199 it is a good change to
make to get another road # out there.