Adding another battery under the hood question

I am thinking of adding a second battery on my new truck. It is a gasser and has the space for a second battery. I am thinking about wiring the second battery to be hot all the time to the truck camper. I plan to put a isolator between the truck battery and this second battery. So the second battery will be a camper battery only. Now somewhere I read where someone said he had seen a lot of wiring burned up on vehicles because people put in batteries that are to high in
cranking amps.

I didn't even realize that was possible. Is it? Because when the isolater is powered and three batteries are all running in parallel isn't that going to be like a ton of cranking amps. So can somebody explain if this is a concern or not.

and a second question is...

I have a 150 amp alternator in my truck. When the two batteries for the camper run down to lets say 50 percent and the truck battery is 100 percent I start the truck. If I turn on the tow haul it makes the alternator put out more power. How does this all play out considering the full truck battery and the 2 half depleted camper batteries. This is on 2017 silverado.

Now this is how I have always done it in the past and haven't noticed any problems but what really happens in situation like this. We only camp occasionally so this is nothing like a full time situation but I am curious.



Thank you!