Those signs should be effective for gun enthusiasts. I still think you should get some people (attractive young ladies work best!)to pass out the flyers comparing Rockefeller/Jay. They can stand at the entrance/exit from WALMART. Have them wear T-SHIRTS that read "THANKS" in big letters, then they can say "Thanks for shopping at WALMART, don't forget to vote on election day." or something. The "THANKS" on the T-Shirts will make most people curious enough to stop on their own.
Don't forget the grocery stores, they may have "OFFICIAL" policies against distributing political literature, etc, but practically speaking, it's up to the mgr whose on duty when you get there.
I've done my fair shair of petition circulating, and most of it was done at grocery stores. If you're nice, and make sure the mgr know that you will be only offering info to people ON THEIR WAY OUT, and WITHOUT ANY HARRASSING, etc...they're usually fine with it.