I will add my support for drivesafe's isolator.
I also use and highly recommend the 2 pin plug that harlie has. You may need to cut the ciggy lighter socket of the waeco cable, but those 2 pin plugs are far better.
You can get the mating 2 pin socket with a similar connection to the lead as for the socket. Or sockets that mount on a bulkhead.
Anderson plugs are better still, but not necessary for what you want.

