You don't need a trigger for supressed, but it eliminates the pain in the butt proper positioning for the doppler or sound trigger to pick up the bullet. I use the trigger whether I'm supressed or not anymore. It's more efficient, rarely ever misses a shot. The only time I've had problems picking up bullets with the trigger, is if I'm shooting from under a low roof. My bud and I built a shooting shack for bad weather, and the roof is maybe 7'? I was having problems. I set the labradar out front the the covering offset a few feet to the left, and it picked up everything after that. Lessons learned. My local range has a 12' roof in it, zero problems there.
As to the saw horse using an offset mounting to keep the unit perfectly aligned with the rifle, it's not needed in my experience. My Labradar will record same velocity whether it's above the bore or 4' L or R of the rifle.