A little more information about Lithium (specifically LFP) and lead acid (LA):
It is true that LFP can be used to 80 or 90 precent depth of discharge without degrading life much, while this degrades the life of LA batteries significantly. An LFP bank needs only to be 50 or 60 percent of the total AH of an LA bank to do the same job. Another advantage of LFP is they accept a very high rate of charge right to the top, while LA batteries acceptance rate tapers off dramatically as they are charged above 80 percent or so. This means an LFP bank can be charged quickly with a shorter generator run or drive. It takes several hours to fully charge an LA bank, regardless of the source of charge. Along with this is the need to recharge AGM batteries to 100 percent periodically (weekly, perhaps) or they will die early. They do not tolerate a partial state of charge long term. LFP on the other hand are quite happy at a partial state of charge, and in fact it is preferred that they be stored that way. The combination of high acceptance rate all the way to full, and tolerance of not being fully charged, makes them ideal for full time living away from shore power.
For many though, these aren't great advantages. In a sunny climate with lots of solar panels on the roof, AGM batteries get charged fully every day. The weight of two 6V batteries isn't very much in a camper and the weight savings for LFP not much advantage. I can live in my camper continuously from two 6V AGMs (220AH total capacity) with 200W solar as the only source of charge (as long as I am parked in the sun). Overnight on a cold night I may be down 40 AH, this is recovered by the solar by midday. Other than LED lighting, I make no effort to save power.
If you needed to depend on another source of charge such as a genset or the truck alternator, LFPs have significant advantage: you do not need to run the generator for many hours periodically to fully charge, and the charging can be much faster (with a proper charger) for less generator run time. Against this is the disadvantage of higher cost and complexity in the installation.
