Low temp and LED’s create special problems. Let alone that the existing bulbs are 5 footers and not common to anything but door lighting in cases. You will have to find LED ballast as well 5 ft lights. What make cooler, as some manufacturers have gone to LED, but I’ve never seen low temp yet. If you can move the bottom socket up for a 4 foot bulb, they are quite common now, as are the ballast. The Phillips instant fit line is approved to -22 F, but are only available in 4 ft and U lamps for 2 ft troffers. They will work with a normal instant start ballast, but not HO or VHO due to the higher voltage and socket design. The LED’s will also be T-8 design, not T12