When marking your equipment, however you do it, put something in a prominent spot so it can be seen. Then add something hidden away someplace. Theif can remove, grind off, torch off whatever the obvious one and not look further.
Just putting something in a hidden spot doesn't accomplish much as the buyer has no clue. Does help in proving it is yours _after_ recovery though.
For entry into the stolen equipment files you need two unique identifiers. Brand/ser No are good. An owner applied number OAN (your DR Lic for example) and serial number (yes you can apply you own serial number to a homebuilt), etc.
Harry K
Harry K