I'm glad to see some activity in this thread! After a summer of experience with my setup, I have a few comments/learnings to share about my setup (GZ Yeti 400 Lithium, ARB 50, 120W Powerfilm panel).
1) Overall, I love the setup. Great ease of use and portability.
2) I mounted the Yeti on its back, with the outlets all pointing up toward the ceiling. This made the panel easily legible and accessible and simplified cord management, especially for the fridge cable, which protrudes quite a bit. It also reduced the footprint I needed to reserve for the Yeti. I wasn't sure the battery would be happy on its back for extended periods of time, but everything seems to be fine after three or four months in that position.
3) If I had it to do over, I'd go for a bigger Yeti. The 400 works like a charm, but was only good for about two days of fridge draw without recharging, and there were a couple times when I really would have liked at least another day of reserve power.
4) The ARB has an automatic shutoff that engages when the DC supply voltage drops below a certain point. With the shutoff switch on its lowest setting, the Yeti would discharge to about 10% before the fridge would shut off. Great! However, I had a moment of stress when I started recharging the Yeti but the fridge never came back on. The reason is that once the ARB shuts off, it won't switch back on until it detects a DC supply voltage of 11.1V or higher, which is higher than the Yeti Lithium supplies even when it's 100% charged. Happily, the simple solution was to plug the fridge into the Yeti's AC output. Using AC power resets the DC shutoff circuit. Once the Yeti was back to 15% or so, I switched back to DC and all was well again.
5) The Yeti Lithium DC charging cable is well worth the $40. WIth it, I could recharge at 120W from the cigarette lighter on my dashboard. I used it whenever I needed faster charging than the 60W available from the cargo-area AC outlet.