Mash tun thermometer

I am using a 52 quart coleman cooler for a mash tun. It holds the heat very well even in cold weather. I have been measuring the mash temp by using a digital thermometer with the cord dangling in the in the mash water with the lid closed. It works, but I'm looking for a better method. Seems like I have seen some coolers on here using a Dial thermometer attached to the front of the cooler with the probe going through the plastic. Most of the dial thermometers I have seen don’t have enough threads to go through the thickness of the cooler and tighten up on the other side.

What is everyone doing ?? Is my digital the best way ??

Thanks for any advice .

Check out bargainfittings.com he's vendor on here and has adapters for the coolers. Great quality and the shipping is darn fast.