Bravo on your success!
that will only work if the heli is close enough or below eye level
Try it above eye level. It looks different at different angles of elevation but it still works. You just have to figure out what it looks like when it's actually level, and you can tell that it isn't level because it will move, so if it's moving change the apparent tilt angle. I guess you could say you have to feel around to get it right. When the heli is far away you probably aren't going to be hovering so you don't need to be quite so accurate about it anyway. It may be useful to paint one tip white and the other black so that you will have some contrast against most any background. Keep up the good work.