I ended up putting in ~1.6L when I did mine and I used a small Allen Wrench. I made sure the fluid was below the fill hole and by the time it settles it will probably end up about 3/4" to 1". Unless you are under the exact conditions Ford was when they defined the specification you will be approximately 1" by following their recommendation. Slight differences in how the trans sits in relationship to the motor to the suspension can cause variation. The biggest issue will be with overfill and much less than 1" underfill. Don't over think this!!!
BTW:
In general, I would not trust the remove / measure method as this puts trust in the guy who installed the fluid in the first place. Measuring is always going to be the best method.
BTW:
In general, I would not trust the remove / measure method as this puts trust in the guy who installed the fluid in the first place. Measuring is always going to be the best method.