Well, it won't really help you because we are thousands of miles apart, but I'd have a solution for that! I often fit white eagle-eye LEDs about 25mm diameter to the front of my bikes to make them more visible, but one batch I bought in from China turned out to be red. My mistake, and I haven't used them yet, but a couple of them as outriggers to the standard rear light would certainly show up, and the OEM brake-light should still make an impact. I'm sure there are other solutions to your problem, but I'd emphasise the need to maintain a significant contrast between the tail light and the stop light intensities.