BBQ Freak
Babbling Farker
You may want to look around at some pics of how big the 5" therms really are, not so sure that's gonna look right on a 50" cooker. ~Just saying.
Plus it looks like you may run into a clearance issue with a 5", have to ask Tyler to check and see if the top latch handle will hit the right door thermometer if a 5" is used when it rotates to the right to unlatch. Looking at your door pictures it sure looks like the top latch will hit a 5" right about 11 o'clock on the bezel.
Mike has some good prices on the 3" glow in the dark Tel-Tru's: https://4thegrill.com/shop/tel-tru-glow-in-the-dark-barbecue-thermometer-short-stem/
I have them on mine and he can see how they look .