Mike,
FWIW, for each individual customer's different choice(s), if you are trying to have satisfied customers, please remember:
1. Some hunters like to hunt with an over & under, some prefer pump guns, some double barrels, some semi-automatic, some single shot, & some like only cameras.
2. Then add to that, different gun brand choices, different gun gauges, different gun chokes, difference sizes & weights of shot in shells.
3. Also is desired length of trigger pull, gun pitch & drop, cast on or off, etc.
4. If cost is not factor, & satisfied customers are important, you may want to ask each person what does he or she want, unless you have enough time on your hands to install a few turn signal kits twice or more because your customers cannot make up their minds.
5. A last emotional wild choice for a Model A owner who is thoroughly confused may be to resort to suggesting "NO" turn signals accompanied with a minimum $5,000,000.00 Umbrella Insurance Policy, with at least one (1) Fire extinguisher & two (2) First Aid Kits under the front seat.