Start in New Sorpigal with a windmaster and gatemaster. Cast Fly, portal to Dragonsand and fly to the village. Dismiss the windmaster and then re-hire the one in a house in the village.

The key to this is that once the windmaster casts fly, she does NOT have to be in your party for the spell to have effect. You get two hours of flying even if you dismiss her right away.

So now Town Portal back to New Sorpigal, get your heals and keep flying back to the island. Fight, fight and when you need healing, get outside the Forge and have your new Windmaster cast fly. Back to Dragonsand, dismiss the gatemaster and windmaster and hire them again. Rinse and repeat.

If you need more fly time you can hire her when you get to dragonsand village, have her cast fly and then dismiss and re-hire her.