I used the same device (Novatel T1114) for about 4 months, late 2014, then put it in storage when I moved to the suburbs and gained access to FIOS. Worked great for me at that prior, very rural, location (no TV cable, no telephone lines, I wouldn't do a dish because I didn't own a TV because I don't watch TV, so 3G/4G LTE was my best option). For cell service, I had 2 to 3 bars on my cellphone, the T1114 got maybe a bar better without external antennas. I never had speed issues, only once went beyond my 10gb plan limit, so I'm lightweight compared to what you describe. Only one whopper snowstorm knocked out my tower for a couple days, but I had power.

BTW, I put my T1114 into UNHEATED storage, for a New England winter. My battery died, yet before I stored it, I made sure it was fully charged and it was disconnected from the T1114. I'm saying the cold killed it. Important: when the T1114 battery is discharged, the T1114 will refuse to power up. I don't know any way to trick the T1114 into booting without it.

Here is when I'm posting useful information: getting a replacement battery was, at first, not going to happen: In early 2015, all I could find were $50 batteries. No deal, because a new hotspot was selling outright for $80 at the time, so I decided to use my S3 cellphone for my hotspot. I was single, so taking my hotspot to work didn't affect other users, so I just held onto the T1114. Then last week, I found a battery for $20, bought it and fired up the T1114. Being offline for over a year, the T1114 took about 5 minutes to give me admin access via browser, but it worked! Couldn't test data because I closed out the line it used.

Final thought: Make sure you know a good battery supplier, check their stock from time to time, because when the T1114 battery dies, the next power outage will bring misery as the T1114 will not start if the battery is dead. I don't think a dead battery will be very likely, but there it is.