Time zone question

first, thanks to all for a great forum.

my question is this:
I want to set up a campaign so that it runs only during business hours, but across all 4 American time zones.

I think I can do this by duplicating my campaign 4 times and setting the hours of each campaign to the business hours of each time zone relative to EST, but I'm afraid the repeated keywords will cause problems. Any thoughts/suggestions/advice or input?

Why go through so much effort. Just set it for the three major US timzones, e.g. based on EST... just set your campaign to run from 08:00 am to 01;00 am EST (New York). This will cover you on the East Coast and on the West Coast from 05:00 am to 11:00 pm. That will likely be > 95+% of all potential activity within the U.S.

The goal for me is to EXCLUDE anyone shopping after business hours. The nature of my business is geared towards industrial, commercial, and military applications. We avoid catering to individuals, and with that in mind, I'm trying to shut down my campaigns immediately after work hours in any given time zone to cut down on average consumers clicking my ads.

My research so far has shown this to increase the cost effectiveness of our efforts. Thanks for taking the time to respond, I'm looking forward to any more advice or opinions!

I guess my real question is does having the same keyword list in multiple campaigns negatively affect those campaigns? It seems to me like this should be ok, because even though they run at overlapping times, each campaign is geographically targeted to a different region. Thoughts?