I think it would be a cool idea if tamed wolves could be able to pull sleds. In snow biome, it could be a basic sled. In other biomes, it could be a cart. That would be really fun putting your dogs into a team and sledding around! It would probably be faster too This wold be such a cool update!
Or you could attach chests! The recipe for that would be
chest-chest
planks-planks
piston-sled