Not sure about the new WSM's, but my 6 yr. old 22.5" WSM has an extra locating hole under the therm that would have to be plugged if I replaced the stock therm. However another option is to just drill a hole for a new therm elsewhere - I know I said the "D" word.... lol.
Drilling a WSM isn't that hard if you take a few simple precautions:
- put two pieces of masking tape or blue painters tape across the point at which you are going to drill.
- use a center punch to create a small dimple so the bit does not wander - a big nail works in a pinch. Remember your just creating a small dimple not trying to drive it through.
- use a sharp bit! Buy a brand new one if you need to.
- and use some cutting oil or 3-in1 oil - heck any type of oil helps, I've used olive oil before.... lol.
- go at a nice medium pace, not to slow, and not as fast as you can - give the bit time to work.
If you look at the link below my signature you will see the eyelet mod I did. I had to drill my WSM for that.