I got the idea for this mod from another post in the Newmar forum and decided to install one for our old cat. She is an older cat that does not go outside so this is a way for her to enjoy the fresh air and watch birds.
I started out with a fold up wire cage 24" X 18" X 19" high. I choose this one because it folds flat to stow away and it has two doors. One door on the end so it can be accessed from outside and one on the side. I started out by removing the side door (just bend the tabs back) to leave a permanent opening.
The I drilled 1/8" hole into the aluminum portion of the window frame. Using #8 X 1/2" metal screws I mounted two U-Clips (had these in my bag of treasures but I believe they are for hanging a heavy mirror) to hang the cage at the top.
Once I had it in place I placed a third clip in the Center bottom, marked the position, removed the cage, drilled a 1/18" hole and installed the bottom clip.
The clips are slotted so they can be adjusted up or down. I left the two top ones are the lowest height. Then adjusted the bottom clip so that when the cage is installed onto the two top clips, the bottom one engages at the same time.
Now the cage is secured by the two top clips and the bottom one prevents the bottom of the cage from swinging outward.
Once all three were tightened in place, I painted them with semi gloss black.