How about something like this:
https://www.amazon.com/ZTE-MF833V-Cu...cUvbUpU7119053
If the Amazon page is accurate with it's description, you should be able to use a SIM card in this and it acts as a cell receiver.
This is how I would suggest to proceed: Buy the device, and use your own SIM to test it. If it works, (and this is me personally) I would buy a full unlimited plan for another SIM card (basically getting another line) and using this setup. If it doesn't work like I think it supposed to, return it, and you are out a couple weeks.
To be clear: Not that there is anything wrong with connecting via HotSpot, but I am assuming the worst that you may need more data in a given month than even some of he most generous HotSpot plans may allow. My idea bypasses limitations like data caps, or speed caps after a certain data threshold is reached.
If you do choose to go this route, I would use a USB 3.0 port, for the data throughput.