No worries - If you need a tunnel bag ....you need a tunnel bag.
Keep shopping and reading dimensions in the adverts.....there are so many of these cases out there you will find something. We have one of the largest, lowest and most flat floors of any scooter!
If you want to be able to ride and dither about in the top of the bag - it would take a pretty tall bag.
Will you be hanging it from the hook, or Velcro-ing it on the floor - hanging it from the crash bars with straps?
Do you need the clear map cover on the top (does anyone use a map any more - or just gps)
This is a good idea ....now you have me shopping.
If you come up with something - please post pix of it.
Givi makes one for Vespas - might it work?
Stig