1:12 gradient is correct guidance for wheelchair access ramps.
It is the minimum I used when designing office space with disabled access.
However it is intended for unaided wheelchair users with manual wheelchairs.
I believe the use-case here is for loading and unloading the unoccupied mobility scooter itself and so the limiting factors may be strength, stability and traction.
It is worth noting that a 5’ ramp would equate to a load angle of around 16.9 degrees and a 6’ ramp 14 degrees, a difference of around 2.9 degrees.
To quote some risk assessment guidance for loaded trolleys on a ramp…
“An increase in slope angle of 1° results in an approximate 1.75 increase in the push force (kg) per 100kg of laden trolley weight. As with any manual handling activities that present a risk to injury, the assessment should consider the task, the load, the environment and the individuals carrying out the task.”
I assume you will use the drive motor in the chair to assist, so if it is rated for a 17 degree (~30%) incline it may work, but this is quite steep for traction as most seem to have an upper limit of around 12 degrees.
I suggest that given the 110kg weight of the mobility scooter, you seek guidance from the ramp supplier.
Please note, I am not an expert, and would advise you to seek expert guidance before trying this, please be safe!