Have you tried straddling the tiller, steering with your knees, while you use both hands to tail the halyard without grinding? (assuming your halyard is led aft)
But, in my honest opinion, if you single hand a lot, I highly recommend you invest in a tiller(auto) pilot. The best investment a single hander can make. Not only will it make raising the sail easier, it will make taking it down less of a chore... plus many other benefits such as leaving hands free for sail trimming, or making a sandwich, or taking a leak....
In any event, a tiller extension won't help as much as you think for this task, at least not as much as a tiller locking mechanism, such as the "tiller tamer"....