I agree if the jury believes there is a reasonable possibility, given all the circumstances, the tail light was broken at 1M, then the CW must fail.
What I am saying is as a practical matter, if the Juror does not believe that to be the case, it is inevitable they must conclude it was broken during the high speed reversing, as no other evidence is before them. Especially the jury should not speculate into existence some other explanation(s) for how it was broken that the defence has not claimed. There really are only two possibilities here, and the defendant knows which version is correct.
I do also agree with you that you can have a version of the trial where the defendant does not advance any positive version, and thus need not establish anything. But given the SERT recovery at 34F which is not contested, the defendant does in fact in this case need the jury to believe to a reasonable possibility both that the tail light was originally broken at 1M AND that pieces were subsequently staged to 34F. Especially because the defendant said this on video.
IMO