I've been using the Home Depot flags for control rods -- they fit the Dubro EZ connectors quite nicely.
I just thought of a crazy idea, but haven't tried it (maybe this weekend): you might also be able to narrow the wire to fit in the FT quick links (not sure if it's easier than drilling out the connectors). After cutting the wire to the rough length you need but before bending your z-bend, chuck the wire in a drill. While spinning the wire, hold on to one end with a piece of emery paper (regular sand paper might work, too). That should fairly quickly reduce the diameter of that end of the wire enough to fit your connectors.