In my first post I recommended just using separate bulbs and wiring from the coach. I like this system because you don't have to deal with another product like magnetic lights. I like to keep the attaching of the toad very simple and nothing interacts with the vehicle's electronics.
Here is another issue. When using a braking system that depresses your brake, many cars will illuminate their brake lights, even when the ignition is off. When using the diode system, which I used on two trucks for many years, you can have issues. When using the diode system and making a turn, if you apply the brakes on a vehicle with the lights that come on while the ignition is off, the brake lights will override the turn signal and wash it out.
On my current Silverado, the brake lights don't come on when the pedal is pressed by my braking system (SMI). I decided to add the extra bulb. The problem is the extra bulb kits usually come with the old style round bulb holders. I went to the auto parts store and bought the new style sockets that use the flat base bulb. These are so much smaller and fit in at a right angle making them easier to mount and take less space. I used a drill and a Dremel to make the opening.
Lastly, I like having an indicator on my dash that tells me when my brake pedal in the toad is operating. That's usually accomplished by tapping into the brake light switch. On my 2012 Silverado, the wiring for the brake light switch was about the size of the wiring you would find in a palm size calculator.....too small to tap into. Then I found no power there when my key is off. So, I added a small micro switch to a bracket under the dash that was triggered by the brake pedal movement. Again, this kept me from cutting into the truck's electronics.
