Here's an indoor outdoor thermometer I've been using for about the past 3 years:
http://www.amazon.com/Acu-Rite-00782A2-Wireless-Thermometer/dp/B0009Y7RPS/ref=sr_1_1?s=home-garden&ie=UTF8&qid=1310543603&sr=1-1

This one will fit between the upper and lower rails on the westfalia stove face plate.  I just use a small piece of Velcro to hold it in place.  The only issue I've had is occasionally it loses communication, and have to reset it. (press in a button for 1 sec).  I got my on eBay for 5 or $6 a piece, but looks like Amazon has them for about $12.

This complements the stove face plate nicely, and looks like it was designed to fit there.  The other one mentioned appear to be much larger. So, maybe there's more than one "perfect" in the world!

Troy