BJ, what I do is leave everything plugged in. At a van park simply switch off the battery switch so you batteries are isolated from the setek. When plugged into 240v your sertek will power the van 12v stuff thru its transformer and your ctek will only charge your batteries. If you unplug the setek then your ctek charger has to charge the batteries AND power the van 12v stuff.
Hope this makes sense.
Cheers
Mike
Trouble if I do that, it stops the water pump from working as it is powered through the drifter so with the battery off, it doesn't have power at that point.
I generally free camp so only do this when running from generator when solar needs a boost. So with no mains water, it need the pump.
To me, having the Setec unplugged, I don't need to worry about anything. Plug the power in and it's all done.
Not discounting what you have chosen Mike, as I can see what works for you.

And at the end of the day, if it works, don't fix it hehehehehe.
BJ