Solar for Van Help

Review the specs for the LOAD connections on the charge controller. Often, they are only rated for a couple amps.
There is an internal switch/transistor that shuts the LOAD power off when the battery gets deeply discharged. You want to keep some sort of low power LED lamp on the battery so you are not totally blacked out.

I'd suggest a pair of GC2 AGM batteries, unless your battery box only holds 1 giant battery. (able to move 2 large batteries easier then 1 giant battery)
(if you are not fully committed to high priced AGM batteries, flooded batteries are good starter gear.

Just to be sure, your AC load is not getting routed back into any AC outlets you have in the Van already? If the AC out is plugged back into the shore power, you end up having the vans DC Converter that is powered by Shore AC power try to charge the battery, which means the battery tries to charge itself. I know someone who has a system really similar to what you are putting together, and he plugs multi outlet busbar into the inverter so his AC power is separate.

I'm not totally sure what you mean here (still learning a lot), but we're not going to use any shore power and the only AC outlets will be through the inverter. I hope that sounds right?

Gotcha, yeah upon checking we will just route DC from the battery instead of using the load on the charge controller. Thanks!

I have a fifth wheel and I am going to plug my Inverter into shore power so I can draw power out of any outlet. When I do this, the DC converter that charges the battery and provides 12 volts to the trailer, starts doing just that. That creates a situation where the battery is charging itself, which I think could be dangerous. A couple of ways to fix it, the first of which is to trip the circuit breaker that has the DC converter attached to and powers it down, which needs to be done manually, or wire a contractor relay so that when the inverter powered by solar power is on, the relay trips to shut the DC converter off.

This is where I found out about this: https://www.youtube.com/watch?v=lqXngyKtZtc

If you are not plugging your inverter back into the shore power to use the same outlets, than this will not be a problem for you. I was going to keep my solar inverter outlets different from my Shore power outlets until I saw this. Keeping it separate would have meant me adding a couple outlets in the RV.

The battery cannot charge itself, be great if it could, everyone would want that setup.
From what I understand, you are worried about you taking in external power, when you are parked up and using it to charge the battery, whilst at the same time you have an inverter running to supply power to the sockets, with those sockets also being fed from an external source ?

Other than being a complete waste of power, I doubt very much if there would be any real problems, apart from the inverter blowing up With the inverter turned on and not being grid tied.In other words the sine wave from your inverter would more than likely be out of phase with the external power. Consider the situation where the inverter is 180 degrees out of phase with the external source, net Voltage = 0, 90 degrees out of phase, half Voltage.

Easiest way is just to put a double pole double throw changeover switch on the input to the inverter. That way you can charge your battery, use the power at the sockets and not have the inverter soaking up and wasting power.

Something else I saw on your diagram, You have everything connected onto the load out. I would only connect things to this terminal which need to be turned off when the battery gets low, to save power. I would put some lights if not all of them direct to the battery, suitably fused of course. You don't want to be stumbling around in the dark if the power was turned off by the controller. Lights growing dimmer are fine, at least you will be able to see still.