We have a 2014 Silverado (new body style) and we DO have to disconnect the battery to flat tow. We have the touch screen radio and do not loose any presets, there or anywhere else on the truck. We simply put the transfer case into N, leave the key in the ignition, adjust the seat to meet the brake buddy and then disconnect the battery. Never have had a problem with the battery running low, even on a trip from NY to FL. We use an aux. 12 volt outlet that clamps on to the battery and then runs into the cab to the brakebuddy. Since Chevy and GMC trucks are identical under the hood and electronically I'm sure yours would be the same. Our manual says that we will loose the presets, but we never have.
