My advice - If you're sure the person you're thinking of asking out will say no, don't do it. What's the point? There is no benefit at all whatsoever in asking them if you're sure they will say no. No good can come of it - only bad.
p.s. if you're in someone's yard, its still casual surveillance, not stalking. If you're in someone's lounge room, kitchen or dining room, its still casual surveillance. Once you enter a bedroom, bathroom, wardrobe or cupboard, THEN its stalking.