The current charger you have, which I assume is an Iota DLS30/IQ4, turns on when you connect to shore power, turn on the main 120 VAC breaker on the camper panel, and turn on the individual breaker for the converter.
When it turns on, it will come up in either power supply mode or charger mode depending on whether it senses the presence of a battery. The mode and stage of battery charging it thinks it should be in determines what it does with the output voltage.
The positive output of the DLS30 is connected to the supply bus bar of the 12 VDC fuse panel. The positive wire from the truck connector is also connected to this bus bar via the Blue Sea ACR. The battery is connect to this same bus bar via the round silver battery switch. I BELIEVE the solar wires coming from the solar charger, if you have one from the factory, are connected directly to the battery so the solar system can charge the battery even when the silver kill switch is off (can someone with factory solar please confirm this?).
So, even with the battery switch off or the battery removed, the DLS30 can function as a 30 amp 120 ac to 12 vdc converter and power everything in your camper. If an AGM battery is connected and the battery switch is on, the DLS30 will sense the battery and be in charger mode, but your camper loads can steal current from it. That’s Ok.
The inability of the DLS30 to charge a lithium battery effectively stems from the higher lithium battery voltage at partial charge being higher than the voltages the DLS is looking for to decide on being a charger or what stage of charging to be in. If you are at a mid level charge, it senses a near-fully-charged AGM battery and seems to come up in float mode. In this mode it delivers about 13.4 volts, and only a few amps flow into the battery. This flow tapers off as the battery voltage approaches the float supply voltage and the battery never can charge fully.
Will the Victron Smart Charger IP22 do the same thing as the DLS-30 IQ/4 then regarding the converting to the 12v breaker panel?
Regarding your last question, it really is best to do your charging from the truck via a dc to dc converter. It will compensate for voltage loss from the wire run resistance allowing you to charge at the full intended current, it will limit the charging current to the intended level thus protecting your alternator, it will control charging to only charge when the engine is running, and it will actively control the charging of your battery. Many of us have 30 amp Victron Orion Smart dc to dc chargers. In my opinion you should place this charger next to the camper battery to minimize the length of its output wire run, and use 6 awg wire all the way from the truck battery to the charger. This means you are replacing the exterior wire run on the camper and a few feet inside the camper. This charger and the solar charger should be connected directly to the battery (not the camper fuse panel) via appropriate bus bars and fuses.
I’ll let you ask questions rather than going on and on.
So the Orion connects straight to truck battery terminals (with an inline fuse) and straight to the camper battery terminals? If thats the case, I'll likely add this instead of using the factory wiring.