Roger.....Under the driver's side window is an exterior bay that has a large black box inside. This exterior bay on a Monaco is called the "run bay". The black box should have three nylon wing nuts holding the cover on. Remove the cover. Inside you'll see all the fuses for the coach.
In the lower left corner, you'll see a large solenoid (round black thing with bolts on the left and right), You'll see two large battery cables attached to the solenoid, one to the bolt on the left and one to the bolt on the right. This solenoid is your salesman switch. When you flip the switch at the door, it causes power to go through the solenoid from one side to the other.
Carefully take the cable off one bolt and move it out of the way, not letting it touch anything. Take the cable off the bolt on the other side, again being careful. Now take a short 1/2" or 3/4" bolt and connect the two cables together. Put a nut on the bolt, tighten it up and then tape all the exposed cable ends and bolt with black electrical tape.
It was not if your salesman switch was going to go bad, but when. Once you've done the above repair, there is no need to make the salesman switch operational again, unless you have some specific need. Many do the above repair long before the switch/solenoid goes bad. It will often fix some other electrical gremlins you may have had because the solenoid was failing.
