I see you are thinking about using a piece of diamond plate or something like that to cover the "ugly area"
IF you go that route, consider just removing that front window and covering over that area . Of all the campers we looked at, when we were hunting for ours that window was the first place I looked for problems. It seems that a huge percentage of campers have problems with that front area not being sealed. Our first Lance did not come with a window in the front and we did NOT miss having a window in that place one bit.
Just an idea and may even help in your decision when and how to cover that area with diamond plate or what ever you choose.
I know what you mean about that delimitation being ugly I dont think i could live with it like it is, but then i tend to be somewhat picky
