It’s not super important, but I have a little dream to have a web camera going over the winter.
Maybe downsize your power needs? Instead of a web camera with live data/communications, could you add trail/game cameras? I have them for photos that last the winter on a set of AA batteries. You would save to memory cards and get them in the spring. For me, it's exciting to drive to camp to see what happened over the winter.
Another option would be a batch upload. You'd need a smarter camera, but could turn on every xxx days and upload to the web. That would be more power, but maybe you could do a weekly wake up, transmit the images, then go to sleep for another week. You could possible have enough battery storage for 6 months or so without charging. I haven't looked to see what's out there. Thinking about a small PC that has the script to upload from the memory disks when it's booted up. Maybe a raspberry pi could do the job?
You could use a timer for weekly bootup, or possibly sense power charging source to upload when there's a charge?
It's sometimes easier to live within your means (power wise) instead of increasing everything to meet your wants.
Here is an article on cellular phone based trail cameras. It mentions the standby mode is about .025a. I assume that's for 6VDC as the camera can run on 4 AA batteries. 12VDC could be almost .0125A.
A pick of the best trail cameras that send pictures to your phone via a 4G cellular network. Complete buying guide 2022.
outdoorwilds.com
Figuring on 12VDC, .025A, that would be about 5 months on a 100AH battery. This is a really small load. You may get by with a deep cycle lead acid battery and avoid the freezing problems of LiFePO4's.
At my camp, I do have some old deep cycle lead acid batteries for a horse fence charger 24/7, 365 days per year (Mouse deterrent). I power a small PWM solar charger off the campers power (LiFePO4) to trickle charge the lead acids. If the main camp LiFePO4's shut off due to cold/ low voltage/no charging possible, the lead acids will run the fence for a year without charging.
I understand this is heading off topic from heating LiFePO4's. This can be moved to another topic if there are issues.