Powered Front Wheel Design

It's a pain.. ok mainly in sand, to luge my tear around by hand. Has anyone setup a powered front caster so you can walk your baby into position with just a finger? Maybe take it for a walk around the park even?
Design I'm looking for would use the 12V battery for power and a pneumatic wheel.
Single speed is fine.
Design I'm looking for would use the 12V battery for power and a pneumatic wheel.
Single speed is fine.
