I think I asked the same question in the first VTA thread and the answer I got was everything needs to be 5mm, chassis and everypart of the body.
To this end, we made a "wand" at our track for the teck station. It is an old stripped spur gear that measures 5mm think. We drilled a hole in the side and glued a 2mm carbon rod in the hole. On tech days we just place the car on the board and confirm that it meets minimum ride height by sliding the wand under the chassis.