small identification mark, adhesive identification mark

new bumper is at home. this can not be mounted with a large number mark. therefore I would like to try if I can get a small number mark. it is clear that I need a entry for this. deeper than the permissible 20cm it would be, about 15cm. so far I only know the layers from the stvzo §60 design and mounting of the official number mark I have seen several kfz with the small number mark. so as example, a8, a4, bora, each front and rear with a small number. I would like to do that now. just how? I would be satisfied with a number in the format of a letter. I have heard so far what about equipment with conversion costs etc., is there something? the tuev examiner on the spot could not give me a precise return and on good luck I don’t want to ruin the bumper… please no advice like: “can you forget”, “what the stupid sense” etc. by the way, my neighbor has a stick character in the size of the shoe I don’t know how to get something like that. I guess I don’t have to mention all this in a legal way, but I’m afraid I’m too expensive for me, or I don’t know how to get something like that.