Any advice for a 9 month old in a hip spica cast? Ride on toys with seatbelt and handle for mom to push?

It must be a ride-on with a seat belt and a push handle for me. It can't be a car with sides. Her legs are out to the sides like a split and then bent down. I need some way to get her out and about. I can't find a wagon wide enough and she really likes to sit up. So a ride on push toy is best. But her feet can't touch the ground obviously. Any suggestions would be greatly appreciated. If anyone else went through this......what did you do? My daughter's cast is very unusual and they don't even make a carseat or stroller for her needs. ADVICE PLEASE????