Thanks guys
I may try the dremel. Need to look at some more as the bottom is lined with 3m double sided tape that I am probably going to mess up on one side.
You can buy small (or large) rolls of the 3M tape ay just about any auto parts store. Heat the existing stuff up with a blow driers and it will usually come off. Then replace it where you need it with new stuff.
This tape is 1/4 inch all the way around.
Sounds like it runs right around the outside edge - which is pretty common. So cut the panel to the new required size, then apply new tape as needed. And remember, the tape is just slightly in from each edge. Run it too close to the edge and it looks like hell.