There is only a small amount of aluminum on the front and back you'd need to cut out. You have to narrow the "step" 3" on each side. It is mostly just woodwork, but the aluminum frame on the front and back is also 3" too wide on the "step" part. A couple minutes with a cutoff saw and some rivets and it is done.
You can see at the start of the build where I had to do that to the front of my frame. Since my camper extends out the back of the bed, I didn't have to narrow the back of the frame.