I don’t have LTE card, just trying to help here.
I my case my Omnia was nearly 70°C, I just connected simple cheapest USB fan to the back USB and pointed it to the lid, and the temp dropped by 10 C immediately.
As for monitoring the temperature, you can use collectd with plugins collectd-mod-sensors and collectd-mod-thermal that will be visible in LUCI http://192.168.1.1/cgi-bin/luci/admin/statistics/graphs
Not sure if it will read LTE card though