I kind of tried what you are doing, but i took it a step further. Instead of making a template of my forehead, I made a template of my hair system front. This way the template matches exactly the front shape on the hair system itself. I used this template to make a glue maker for my head. this way its not only the right distance but the glue shape fits as well. i do not use this method anymore because i like attaching from the back first.