The best example of a clicker trained dog that I know personally is Lynn Gardner's Aussie rescue named Maggie Mae, in Ontario. Maggie's owner has trained her to recognize over 200 cues, and often does clicker demos with her in schools.
Maggie's click is the blink of a flashlight, just a regular pen light pointed at her; and most of her cues are American Sign Language words. The trainer holds the light in one hand along with the target stick, if using one, and treats in the other, just as we do with target and clicker. The dog has to be watching the trainer to see the blink, but she watches very carefully, you may be sure! Once when Maggie was sitting in front of Lynn, at attention, Lynn gave her a hand signal, and the dog rolled over on one haunch and scratched herself. I couldn't help but ask, "What was THAT signal?" "Relax," said Lynn.
If you were working at a distance and outdoors you might do what the clicker training falconers do and use a photographer's strobe flash light. That shows up for miles, I'm told. You could also use a touch. One year at the Assoc. for Behav. Analysis meetings I saw Mark Lipsitt do a beautiful demonstration of clicker training, with a field-type black lab, using a quick tap on the dog's cheek as the conditioned reinforcer. The dog did lovely off-leash work in a crowded lecture room. For a click from a distance, such as when the dog was being released from a stay, Mark just darted over to the dog and tapped it, then went back to his position while giving the next command.