9 times out of 10, I can get my main to hook on first go without too much drama, the last 100mm or so takes a stretch to push it up because I at full arms reach.

I have a piece of that evo foam (comes in 600mm x 600mm squares and interloacks for soft foam flooring. The piece is approx 20mm long and 12mm thick and wide. It is squashed in under the shackle between it and the sail, this holds the ring upright but still able to spring back when it hits the hook. Before I push up the sail, I make sure the is as close to centred as I can and I have the top of the ring about 6mm from the back of the mast track, this is about right for when the ring hits the hook and springs back to lock in place. If it won't push up or is difficult, spray a run of silicone spray the full length of mast before you put the mast up. It can help. Have the boat/mast pointing dead into the wind it makes a lot easier, if the wind is swinging a bit, I find it easier to stop and wait for it to settle for a second, on my old sail i did the tiller extension thing, but hated doing it and won't do it anymore with my new main, it worries me too much.