Wingnut,
I've got the very same boat and had the very same problem. Great minds think alike...
There was a thread on the Robalo Owners forum a few months. Here's the link:
http://www.robaloboatowners.com/foru...?t=140&start=0
In short, get a pice of vinyl that's 54 inches by 3 yards long. Cut it in half the long way so you end up with 2 pieces 27" wide and 3 yards lond (the pleats will go the right way, don't worry).
I sewed the ends and stapled everything back together (using Monel staples). It looks better. Not perfect, but better.