Well what I was planning to do was make the 0.9% solution simply by weighing the salt and water till I read your post.
But of course it will work. And if I were you I wouldn't wait on mine or anyone else's endorsement before trying it. No more than you would use in a recipe, the salt will hardly be noticeable or impact your sodium levels in your body. And if you're using sea salt then you're avoiding unnecessary additives found in table salt.
I have several recipes that are just missing a little something. So if 0.5% saline is the trick, well that's only 0.15 ml in a 30 ml bottle.