To give you a comparison, we paid $1040 labor, and purchased all our own parts online. The labor charge included installing the base plate, the Ready Brake cable, break away cable, bulbs in tail lights, charge line, and monitor on motorhome dash. They also spent time testing and tweaking everything between the car and rv. The whole job took about a day and a half.
While your estimate sounds high, going through the firewall definitely would have put that portion of the job at more than 2 hours.
Hope you are set up and ready to go soon! :)