The range is fine, the thermocouples will go down to -200C and up to 980C. The accuracy of thermocouples in my experience drops at below zero temperatures, but it is still serviceable.
I don’t see any limitation on creating your own VI. It’s basically opening a TCP socket to the Wireless to Ethernet Modem and parsing the data that streams out of it. I’ve put in a request to release the source code for our LabView utility. You may be able to take out the chunks of code that parse the data. It is built for the USB Modem so you’ll need to abstract the transfer protocol for TCP, but they stream fairly similarly from a software perspective.