There is getting to be way to much self serving diversion and confusion going on here, I fear.
Bottom line is that we want to help the OP make the right decision for his system. He stores in an unheated space with one warm wall in Minnesota. He thinks he wants lithium but isn't positive on that I think, the storage area is said to never go below zero degrees F in the winter, he wonders if he needs heated batteries and didn't mention what type of heat desired if he did decide he needed it.
It appears that with the listed storage conditions his lithium batteries would be in cold weather, no charge, maybe no discharge mode and would need to be warmed up before leaving home if use of the batteries is wanted before getting to warm weather. They should not need heat when stored as above the -4*F said to be minimum storage temp. My conclusion is that heat would be needed if use wanted upon leaving or some time after that before getting to warm area.
What style and how controlled has many options from manual to automatic, heat from batteries themselves or shore power or alternator power or whatever other way that could be devised. IMO, this is the main thing that the OP needs to be able to figure out if he wants his heat system to match his use patterns and needs.
So I think that the OP and the rest of us need to do a reset here and find out his needs and wants before going any further with all this other stuff. Without knowing what the OP desires going to deeply into often complex discussions will just be confusing.
Keeping lithium warm enough is a big deal if you are from Minnesota and doing that heat may or may not be a disqualifier for different people. Depending on the needs and wants of the OP, it could be inexpensive and probably manually run or increasingly expensive and complex as automation and redundancy is built into it.
Thank you for this post!