I still have the aluminum dash plate out of my Argosy as I'm not quite ready to re-install. I'm sure I could get a fairly accurate tracing of mine if that would help. I would just need to find a long enough sheet of brown kraft paper to make the tracing with.
As far as removing the vulkem I used this Multi-Tool
with a scraper blade on it. It's amazing how well it removes vulkem without really damaging anything else. The one thing you can do to help with the scraping process is to make sure all of the screws and rivets are removed.
There are many other brands out the with Fein probably being the best but I have several Porter Cable tools and since purchasing this one I've used it quite a bit working on my Argosy. It's done everything from scraping vulkem, cutting wood, removing rivet heads and cutting square holes in aluminum skin.