Absolutely, LiFePO4 batteries are a solid choice for affordability and durability in off-grid setups. Your system sounds like it’s perfect for your buddy's needs, especially with its straightforward setup for essential utilities.
When handing it over, maybe check the positioning of the solar panels for optimal sunlight exposure, and ensure all connections are secure. How long has your buddy been living off-grid? Also, are there any specific challenges he's faced that you think this setup might help overcome?