Congratulations on a nice KISS UDS!
I used a metal valve stem (minus the valve) for the thermometer hole. It's a perfect fit and it's chrome plated.
The 1/2" water-tight Halex conduit connector is perfect for the digital probe wire.
I also did my charcoal basket like yours, using the lower "water pan" grate to hold the upside-down basket for grilling. I had to add some more intake holes at the new charcoal level to get good grilling temperatures. Now it works great.