Ah yeah, I have seen the inside of these trailers a couple times before. I forgot about the
fiberglass cabinet. Your idea of using a metal plate to extend the size would work, but it would probably not blend in well, and take away from the original look as well. My first thought would be to try to find a stove and icebox that would fit into the existing opening or ones that would require a minimum increase in the opening size. Is this not possible?