I added (after I first installed) an isolator to the various 12v FB loads. The USB and other bits have a small drain which meant my battery was constantly going through charge cycles even when not in use. That’s very much cut down now (not eliminated, as it has its own Bluetooth).
You could also run the earth for various 12V stuff to the nearest earth point on the van. I did this for my 12v lights which halves the amount of cable to buy, and helps with voltage drop.