I will weigh in w/my experience so far with Lithium. I have a 2018 Grandby Shell on a 2018 LB HD Ford F-150. Heater, stove, couch.
I purchased a 100Ah & a 50Ah Lifepo4 with internal BMS & Bluetooth. My 50Ah will double with my canoe to power electric trolling motor. Weight was a concern with me. Handling & storage. Wiring as well. I disconnected the FWC power lead from my truck battery, so my 12V System is isolated unto itself. My 12V draw is Led lights, furnace fan, Dometic CFX 50 W. I will be adding a 1gpm Shurflo on demand water pump for a Ronco 7 gal tank.
I have two120W Solar blvd flex panels mounted on a custom build aluminum tube frame mounted N to S in between my two vents. There is room for a third panel. The frame is mounted to my Yakima tracks. Everything is run in parallel. Roof setup weighs 15 lbs, less than 20.
My initial 3 trips, with my coldest last week, Lundy to Monitor, has not used more than 10% to 12% of the System. The Bluetooth is really cool with my phone. It gives me overall usage for both batteries & can look at the individual cells as well. No external battery monitor needed. I have a Victron Smart Solar 100/30 mppt. My controller is mounted inside my battery box. It gives me daily monitoring plus 30 day history, again, Bluetooth is really cool with this too. My usage seems to be replenished in just a few hours usually from late morning to early afternoon.
A Renogy sae roof coupler to two mc4 y branch connectors runs my roof in parallel. I live in the SF Bay Area, so long term cold will not be a detriment. But it can get warm, it was hotter than normal this summer. I need a shade canopy. I did all wiring myself, idiot proof.
I was given great help in my learning process from Vic, Craig & Rando in particular. I was, & still am, not well versed in electronics. I have learned a lot. I wanted to keep things very simple & off grid. I purposely did not go with the FWC build in order to be light. I did splurge on these 2 batteries but did get small initial discount & a better discount on the 50. I am really happy so far. I am a guinea pig with this setup.
Hope this helps any considerations.