People also burn 5 kw transformers and the truth is that you can make horror story to every subject.
As long as you do it right way, you will be safe.
I do have mechanical degrees, so don't take me as expert, but that is what I learned mostly the hard way.
-use battery combiner, or ignition-activated relay connection from alternator
- put fuse or circuit breaker adequate to the cable you will be using
-I understand this is going to be 2nd battery parallel with the one in the camper, so you might not need heavy cables, but nothing wrong with over-sizing.
