Naa, you told me to harden up!
It's actually quite okay in there with the windows open, plus I like to store things up across the rafters, which sisalation would interfere with. As I said, it's mainly a storage place and I work on the deck. My table saws, routers, and mitre saws are all portable, and I have the portable power vice, so 12 metres of shaded open-sided verandah is a great work space for them. Just leaf blow all the sawdust off onto the grass, and the clean up is done. Works well.
Next steps will be walls, windows, noggins, battens, some clear waterproofing on the FC, fit the door, and then the little polycarb side roofs. Another week should get me there, but first I have to go sailing again.