I wouldn't suggest just cutting a hole or whatever, but you can use the sensor. NIke, among others, sell little pouch-type deals that you can put the sensor in and attach to your shoelaces.
Wish I wasn't such a heel striker. My LG3s might've lasted a lot longer than 400 miles. Almost flat in the forefoot like yours is, and a ton of the black rubber worn through. Not fully retired, but out of the main rotation.