I think some on here have mobility scooters, but probably charge them from hookup or inverter. Also quite a few have electric bikes, and I think also charge with an inverter. Looking at the MobilitySmart website there seems to be a number of chargers available that will work from a 12V cigarette-lighter type of socket. You would need to get one suitable for the battery in your scooter - there are many different types and sizes of battery.
Basically you need to know the size of the leisure battery compared to the scooter battery. If the scooter battery is half the leisure battery or less, then there's a good chance it's possible. And if it's not you may be able to increase the leisure battery size by adding an extra battery. Do you have an idea of the size of your leisure battery and scooter battery?