Yup - off the cliff it goes!
Just buy it back and sell it for cheap to someone who lives close to the ocean.
Crazy heater core locations are inexcusable and I'd love to torture the people that design such a POS. I have done an F-150 that was a nightmare and a VW Pas**** which needed the evaporator taken out / the a/c system vented to get the heater core replaced!
That's one advantage of an aircooled car - no heater core!
G