They would have to be wraparound and secured by velcro or cable tie or similar, because it's almost impossible to slide one over the spring due to how the kingpin & stub are assembled. Something similar to the old A series by-pass hose but bigger would work, but wraparound rubber won't seal very well unless it's superglued.
I still think that mohair is one of the best fixes, because it's cheap, simple to make and lasts well.
