I'd think that the string wax wouldn't hold the head tight enough, once you got it aligned to the fletching, as it would most likely still not be tightened all the way 'home".....

If you're adamant about having the blades line up with your fletching then I'd strongly recommend going to a hardware store or a plumbing outlet and getting some small rubber washers - just big enough to fit over the threads of the broadhead. Screw the head home - against the rubber washer - and it'll stay where you leave it.

Personally, I've never worried about having the vanes and the blades line up. It's just never been a problem. 90% of today's broadheads are either of the compact design or they have skeletonized blades that don't wind-plane. I still believe that your problem stems from when the arrows were first built....