People do carry lighter mobility scooters on tow bar platforms but you need to be very careful not to exceed the noseweight of your tow bar and to make sure that it is properly secured.
Here, a mobility scooter is secured to the BUZZ RACK Buzzpro P10 multi-purpose tow ball platform:
The Buzzpro P10 platform takes a maximum load of 75kg and weighs 12.5kg. E,g, if your vehicle had a tow bar with a noseweight of 100kg you can take a 75kg load on this platform. If your tow bar had a noseweight of 75kg you can take a load of (75 - 12.5) 62.5kg.
The BuzzPro P10 is adjustable in size, so you'll also need to check that these measurements will work with the shape of your scooter:
