The Piaggio BV350 scooter seat also has a more pronounced, straighter butt stop than what is on the CTX, which I liked slightly better than the CTX's slanted stop, but on the Piaggio taller riders couldn't stretch out as well as on the CTX. I'm 5'8 with a 30.5 inseam and sometimes even I would prefer to sit back farther on the scooter than the stop would allow. However, on the CTX the stop is so far back for me that I can't really sit back far enough to take full use of the stop anyway, so even though I'm missing the more pronounced butt stop, it would have to be slightly farther forward for me to make use of it.
I went a different route to give myself back support. I mounted a top box with mount and back pad directly on the pillion seat via lashing straps. There was some flexibility as to where I could mount the top box with respect to forward and back, so I placed it right where I needed a stop for maximum comfort. This gives me the option to sit slightly forward for city riding with an arched back and more control and then sit back against the backrest once I get out on the open highway.
If I want to carry a passenger, I only have to remove the seat and untie the lashing straps and reinstall the seat. About a five minute job. My system also saved me the expense of needing a rack for luggage, however, I don't have the option of a passenger and luggage without a rack. But since I'm almost exclusively a solo rider this is not a problem.
