I’m sure you’ve thought of this, but check out a store that specializes in hiking gear. I’m sure you can do it online.
If I don’t find something suitable at Borders, there’s a map store down on the waterfront that I may try. If it’s still open. The stores there depend on the ebb and flow of the cruise ship tourists, and it is the off-season. If not there, the pirate store might have something..it’s one of those places that gets a new item of use every few weeks. Last month there were several cutlasses, some of which were fairly historically accurate. I didn’t buy one, because it would count as a weapon and I’d have to keep in ship’s armory so there’d be no point to having it.
In any case, there may be a map there that would work.