My concern for the OP would be having lfp batteries on the outside of trailer and doing long extended camping in cold weather were the temps do not get above freezing for extended periods. Even them being in a a cooler like a Yeti or Otter would still need extra insulating even with the heat types of batteries. I have a 65qt Otter box cooler and it does keep ice pretty long but can also freeze water in the bottom of the cooler when no ice is present during the winter months in the back of my inclosed truck. Any of these "well" insulated coolers will need more insulation and the coolers aren't cheap to start with.
If lead batteries have been working for you under these circumstances I would probably stay with them.
