There's a battery at EACH END of that black wire
so there should be a fuse at each end. There's a 30 amp fuse in my truck and a resetting breaker by the battery in the Casita
Every time this subject comes up there's a big discussion about what type of connection is best, approved, not approved, as done in the military or in short each person's preference. From there it branches off to what crimp tool is better.
One thing is for sure almost ANY THING is better then 3M insulation piercing connectors
Nobody is going to convince anyone their way is better
does not have a monopoly on the rats nest where the 7 pin cable connects to the trailer. A long time ago I installed a terminal strip protected by a box mounted in the closet where it's dry eliminating the Casita's original rat's nest covered by a piece of "Casita wood" that takes up a good amount of floor space in the closet. Without the rats nest it's not needed
I used crimp on connectors that I soldered too then covered by heat shrink tubing that there is also a debate about what kind is best
I was taught a connection needs to be both electrically and mechanically secure. Common sense tells me it should be protected from the elements.