Just been trying out the RUT850 and it seems to work well off 12V - Have a Three Data SIM in it - does up to 4G LTE with diversity, and has a WiFi. We have a diversity antenna on the roof.
Will even work to another WiFi hotspot and do back to back WiFi with 4G as a backup, or vice versa.
See here for details
Just as a note - also now using Freesat with a small Humax decoder HB1100-S which i got from Humax Direct - not only does it do 7 Day Programme Guide, runs of 12V, but also is playing loads of videos via a plug in SSD Drive on the USB port .....