I've ran TrueTracker with a Sunco AcuraTrak 3 point hitch for 6-7 years on my planter and row crop cultivator and I have either moved the NAV from the planter to the cultivator or more recently put a dedicated NAV on each machine.  It still creates some calibration issues.  I recall seeing pictures or literature in the past with the NAV mounted on the hitch itself.  Does anybody have experience with this?  I've used Trimble equipment for many years and it is my understanding that the NAV's responsibility is to compensate for roll and terrain so I would think it would be find.  The only difference it would have is that it would be three feet further forward and maybe a bit lower.