Hi John,
I do not have the same model that you do, but we had an awning added after market and it's worked out very well for us.
First, our 5er has a rear door on the opposite side of the trailer, and it's the opposite side we had the awning added.
Before we signed for delivery of this camper we made sure from our dealer that one could be added, and approximately what it would cost, and how long it would take to do it. We also wanted flip back handle for the back door, like the front, and wanted the same LED awning lights as the front. Our dealer assured us it could all be done, and before we even took delivery we set up an appointment to have the work done. And everything worked out fine.
The biggest decision we had to make was where we wanted the switches. They asked us if we wanted them outside or inside the camper. We wanted everything inside. We ended up with 3 switches on the side of the dresser cabinet in the rear bedroom nearest the back door. It's actually just an arms length from the door and I can see the awning clearly when extracting or retracting it, either through the door itself, or I can see the arm closest to the rear of the camper through the bedroom window. There is a switch for the awning, the LED strip lights now attached to the side of the trailer and the Dometic power strip added to the awning arm.
Wires were through that hallow space under the floor of the trailer, along the outside of the frame. I don't know what that's called, the rounded "skirting".
After the work was done, I secured the wires a little better. To me, it looked like they would eventually sag and rub the tires in the wheel well. I ended up tucking them between the main trailer frame and the floor of the trailer, then sealed them in place with gobs of liquid nails. Once the liquid nails dried, I sprayed it with black Rust-o-lium so the liquid nails would not be noticeable in the wheel well.
Now, we have an awning on both sides of the camper and can park any direction, as either door on either side can comfortably be used as the "front" door. And for what it's worth, when parked at home, the back IS the front, and when camping, the front IS the font. Now we can use the trailer parked either direction.