With a scooter you have a low step in position, so you swing your leg in front of you at step in. The low part in the frame where you have to raise your leg is only 48 cm from the floor. This was one of my reasons to go to a scooter as basis for an aerobike. If you can make a low section by reducing the tank size you might be able to do the same step in. Cutting a part of the tank sounds a little drastic. Maybe make a new aluminium tank ?
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