Modern US decals are pretty easy to replicate. We tend to use a variety of stencils for the bumper markings. There are numerous dry transfers at a model railroad shop or arts store that are suitable for 1/35 scale. Take a look at the photo you want to replicate and dry rub your own markings right onto the vehicle or put them on clear decal film and apply them like regular decals.
Also if you have access to a regular black laser printer and have clear decal film, you can make the markings using something like PowerPoint or even MS Word and just print them onto the clear decal film.
Either method should not be a bridge too far for even a novice.