Now Austin is going to have 3 Classis MH's?
If your electrical horns are in a similar location as the air horns, you may have to remove the inside wall panel to the left of the drivers seat under the window. Most likely the wires are going inside of the first roof frame at the rivet line and then down the side inside the wall.
An easier way might be to pull the horns and run a new wire into the first overhead cabinet behind the drivers seat, then down the side for a couple of feet.
Glad to know of another MH forum member in Austin. I will have to come see your rig.