I hear you Langley968 but I don't have the same problem with any of my other 4 cars and they are a relatively diverse group. They all have a section of non colored glass in their rear light clusters rather than the all red in the 968's case. When lit, the 968's reverse light reveals that the lens in front of the reverse light bulb is not uniformly red but rather striped red and uncolored. This feature makes the 968 all red clusters look better than the multi-coloured lenses on my other cars. Nevertheless my 968 reverse lights do not emit nearly enough light in my opinion whether with which to see or be seen.
Thank you willamoss for sharing your solution but I am a stickler for "stock" and I am also not sure your solution will be considered street legal.