These bucks actually work very well up to 300mA. Don't expect anything higher than that and you are good to go. You don't need to cut a trace on the pcb, just solder the bridge one voltage step higher than you need. F.i. if you need 5V solder the bridge on 9V. Maybe a little bit of trimming is needed. You can do this via the small potmeter.
very good and received vrey quickly