First: that tissue should be put on dry and then shrunk. It has a powerful shrink when put on wet (but, you haven't warped your wing, so it's OK -- right?)
Second: use multiple coats, until you're sure it's sealed. If it's Sig and it's thinned 50-50, I'd use three or so. It won't cloud up any more or less than if you're putting it over a normal dope finish (so avoid humidity, or use retarder), and if it does cloud you can use the techniques to un-cloud it that have been mentioned here over and over again.
If you have darker tissue you can cut markings out of that -- it ends up looking pretty good that way.