Dan asked: How and where is seat measured to, on electric assisted bicycles? And what adjustments are acceptable? While the seat post of the saddle on my 2-wheeled semi-recumbent, barely reaches a somewhat acceptable height, it requires tools to so, and perhaps a change of seat post for safer stability. And my full-recumbent trike not only requires tools, but also a headrest, and/or spacers to incline backrest more vertical to meet height requirements if measured to the top of seatback. Are these acceptable? Must I be prepared to readily demonstrate adjustment?
Lacking any case law or legal opinions on the seat height, all we can do is use the actual statute, which does not answer your specific questions. My guess is that the height of the seat is the present height and not a possible adjusted height.
Please see this post.