Looking at your photo, I wonder if you have enough room above that small window and the roof to actually put an awning roller without interfering with that window, or covering it.
The second problem I see, is where do you put the uprights. There's no room forward of the door and I'm pretty certain you would want the awning over the door.
Those older campers were designed for the awning, usually a fabric of some sort, had to slide in that slot and was supported with tent poles and rope. Every time you took the awning down, it had to come out of the slot and put away. They were a real pain in the neck, for sure. I remember my parents 1963 Phoenix. Dad was over 6 feet tall, but still had problems sliding that canvas into that track. After a while, they quit using the awning completely because it was just too much work.
An alternative, and a much more logical and cheaper approach would be to use a "quick shade". We carry 2 of these with our camper all the time. Opposed to the expense and the unknown of how to attach the awning to the camper without causing damage, this is a much better solution.
Click here.These are currently available at WalMart, priced between $45 and $110, depending on how big you get.
We are on our 2nd and 3rd quick shade. We got our first for our pop-up camper. It lasted 15 years and finally the fabric just shreaded one day. We replaced it with 2 more. They are 12 foot instead of the smaller 10 foot. We use them with our awning for added shade, or to make shade elsewhere, depending on how and where the sun is shining.
So, as an alternative, you might consider something like this. Cheaper, easier, immediately ready to go, and no modifications needed to your camper.