Not to mention in a real sniper det, the spotter is usually the Senior Sniper of the Det, the man with more experience. Like Disco_Dante said, you would have to find someone that is willing to take you on, and event hosts that are willing to allow you to be in play on the field, even if you are unarmed.
6 Section, 2 Forward Observation Unit Airborne, Royal Artillery
Level 2 Certified BA Sniper
Sniper Instructor (Fieldcraft)