Harbor Freight sales a 500 lb. Capacity Aluminum Mobility Wheelchair and Scooter Carrier that attaches to the receiver hitch if you have one. Price is $169.99 and you should be able to use one of Harbor Freights 20% off coupons brings the price down to $136.01 .
They also have a 400 lb. Receiver-Mount Motorcycle Carrier $124.99 that looks pretty nice and should be able to use the 20% off coupon on it.
The 20% off coupon is easy to find.
Both carriers also have a ramp to help load and unload the scooter.
Use the Ratcheting Tie Downs to hold the scooter in place and cover with a tarp. Be sure to use straps to hold the tarp tight in place.
You can look up the carriers on line by googling Harbor Freight and typing in carrier in the search window.