Well, since you can find coordinates for individual points, you could manually digitize the route to whatever precision seems sane, and maybe download maps with a wider radius than normal to ensure coverage. That should be easy for the long stretch down 307 (I assume that's how you'll go), but planning a route out from the airport may not be so straightforward.

That doesn't give you a "real" route, for, e.g. turn-by-turn, but will get you the maps. It sounds like you have a navigator for directions, so I hope she's better with maps than with priorities!

Enjoy the sun!