Sounds interesting, Don.
Have you done any sticky board tests before, during, & / or after?
I'm happy that your bees look good and that you pulled a crop.
But measuring the daily natural drop and the 1st 24 hr chemical drop will give you a lot of information about your experimental treatment.
Also, where did you come up with your recipe?
By taking mite drop measurements you should be able to adjust the ratio up or down and dial it right in.
What is the product name of the NEEM?
I have exactly ONE hive more than you.
That makes my opinion beyond question.