A set of small trailer wheels that can be adapted to a solid axle is the plan. Or golf cart tires. Needs to be a solid axle from what I've seen on others info. Adapting a sprocket to the winch is gonna be the biggest hurdle.
Found some split sprockets with 428 Chain. Seam like they might work. http://m.ebay.com/itm/30mm-Go-Kart-...Tooth-WH171-/181845141502?nav=WATCHING_ACTIVE
Don't have my caliper for some reason, but I measure it at 1.25" or 32mm. Trying to find a split axle sprocket at 1.25/32mm. I could have the drum turned and cut for a keyway or I need to find a way to bolt it to the side flange on the drum.