Over the past three weeks I have been stopped twice in HCM and three times outside HCM - twice during the day - for 'light' checks. I do about 3-4,000 kilometres a month. There is no language 'problem' (or escape) - one CGST operates your light switch and the other observes your lights.
I popped a headlight in the An Giang 'smuggling zone' a few days ago. I stopped to replace the defective light and a couple of armed hairies (border police) crawled out of the bush to check the action.
You can buy LED replacement side and tail lights on Calmette (Cho Dan Sinh area) as well as on the side streets of Ta Uyen in Cho Lon. LED lights rarely completely fail and will prevent you having to donate to the CGST 'pension fund'