The All-In-One harness is a universal, user-configurable harness. Jumper settings are provided that allow the user to customize the operation as desired. Do you want your Halos on during the day but not the DRLs? no problem, you can do that. Do you want your DRLs on at Night? no problem. Do you want to use a switch to control your DRL's at night? no problem.
It may be over-kill to buy this harness just to control the side markers, but you can use it that way if you'd like.
It makes sense to convert the front marker lights into dual intensity running lights / Turn Signals. The reason is that the front turn signals on the Camaro are recessed into the grill and completely blocked from view by cars, bikes and pedestrians that are located to the side of your car. When you are intending to turn in their direction, they will now be able to tell because the front marker light will blink. This is a great mod in so many ways. It really isn't needed for the rear markers, in our opinion.
There are no issues with the "match" between the new dual-intensity LED lights in the front with the stock marker lamp in the rear. The normal-intensity mode of the front LED lights is equal to the stock marker lamp bulb that it replaced, so it matches the rear intensity extremely well. The High-intensity mode of the front LED light is significantly brighter than the rear.
However, if you were to install this harness on a car that has LED Marker lights installed front and rear, it will reduce the intensity of the front markers for normal operation, and will use full-intensity mode for signaling turns. The rear markers will always be in full-intensity mode, so that might look odd. There are some simple mods for the rear LED markers that could be done to reduce the intensity to match the fronts, but it would require some experimentation. PM us if you'd like to explore this option.