The reality is that modern (meaning LTE) public networks are more secure today, than they have been, its also trivial to bring an LTE base station with you now - with the hardware at this point being no more complex than a controller driven wifi network.
Indeed, I have an LTE base station in my office, on perpetual "loan" from T-Mobile for US$25, providing us with LTE service in an area where they have no service. It's roughly the same volume, or a bit less, as our modem/router.
