Just go to Murmurwoods get the stone to flesh scrolls, cast invisibility from the scroll and run to Cauri. If you are quick and know where she is, you can make it on the ground, unstone her, and hightail it back to town before the invisibility spell expires.

I have done it this way many times . . no need to have fly to get Cauri and once you have her in the party. you can buy a fly spell since she is already an air master.