(the sketch already constrains equal flat areas with the two equal diameter reference circles. I use the ID from the provided cosmetic thread to determine the offset)
Although it has always been PTC's stance that threads need not be modeled, they work really nice when grown using a quality 3D prototyping system when you don't have the particular tap on hand. They also help in some instances where you want realistic images or diagrams where you want to distinguish between threaded holes and through holes.
A great improvement to the software would be to allow toggling between cosmetic and actual threads. You can add to the votes if you can access Ideas here: Thread ideas: modeling and drawings