Don’t use that or any battery isolator.
They have some voltage drop and are failure prone.
A continuous-duty solenoid is a much better setup.
You can control the solenoid however you like.
I’ve done it with a wire that’s hot when ignition is on, with a manual switch, and I’ve even used an oil pressure switch (you switch the ground to the solenoid instead of the +) so it only connected when the engine was actually running.
Use at least 4-gauge charge wires to your camper batteries.
I use 2-gauage. Your batteries will charge great from the truck that way.
You’ll want at least 2-0 (two-ought, rather huge) cable from your batteries to your inverter to run a coffeemaker. Even bigger is better.
Sometimes when wiring inverters I even double up and stack two positive and negative cables. It really does make a difference.
Be ridiculous about the battery cables.
