I wouldn't want to use a candy thermometer because, if you're lucky, you wife is going to use that little sucker some day in the future.
Actually, it sounds like a good idea if you don't plan to use it again. But it's going to be a balancing act to keep it in contact in order to get a dependably accurate reading. And you'll never know if it's accurately reading your iron's face. It's designed and tuned to read when immersed in a fluid, not just near or touching a hard surface at one very small point. And (BLUSH) I know personally that little thermometers like that are really hard to keep in contact with my... uh.... your iron. (And if I remember correctly, when I got the little Coverite dodad, it read higher temps than my... uh... your candy thermometer did... uh... would.)
Now, personally, I've always enjoyed solving dilemas like this one by going over to Lowes Home Improvement and buying a tool that solves the problem. And last time I was in there, they had this "point at the thing, pull the trigger and record the temperature" device/thingie. I figure it'll be the perfect new tool to have because I can also do lots of other things with it (I just don't happen to be able to figure out what else right now) and mainly because I don't have it now. Oh wait! I can check head temperatures of my glo-engines, and maybe exhaust gas temps!!! Hey, hope you get some better advice, I've gotta go.....