Have you seen this? I was thinking it may be a great option for my trailer. I am seriously considering adding a couple panels to the roof, so the battery can always be charged if if the trailer isn't plugged in to shore power. This would just add the ability to charge from the truck while connected (albeit at a pretty low amperage rate).
DC-DC MPPT
I dont know if Renogy had a multi-input charger like that when I was looking, but RedArc(the same people that made the brake controlled I put in my Lexus) did. The issue with RedArc's, and the issue it looks like with this one, is that they can only accept 25 or 32V from solar.
This is redarcs. It also can charge from 120V shore power.
REDARC's Manager30 is a 30A state-of-the-art battery management system designed to charge and maintain auxiliary batteries for recreational vehicles and suits all battery types. Discover more here.
redarcelectronics.com
When I was asking about charging for the LiFePO4 on the Jayco forum, one of the guys said that his 2x100 Watt 12V Renogy panels will routinely put out 40V in series. The reason you want to run the panels in series is because you want the panel voltage to be higher than the battery voltage, and if its cloudy or if its morning/evening when the sun is lower in the sky, the panels output voltage will crap out and you may fall below 14.4V that the Li batteries peak at with the panels in parallel.
That Renogy Rover 30 Amp MPPT solar charge I bought can handle 100 VDC input from the panels.
So one of those multicharges would probably work fine if you were just using it as a float charger from the panels and are fine with it only charging on sunny days in the middle of the day. But if you want to get all day power to your batteries and are using it as a primary charging source, I think you need a standalone MPPT charger.