UPDATE: I think I have the outline of a plan, which looks mainly sensible when viewed on the screen of my phone. We'll be moving just down the road to Amelie les Bains this afternoon, where I'll hopefully be able to buy a suitable map.
I think I jinxed us by booking flights home and saying that all we need to do now was to finish on schedule. It didn't seem that outlandish a thing to do with only around 45 miles remaining and 3 days in which to do it.
Then I woke up at 4.30 this morning with a massive headache and a tummy ache. It is now apparent that I won't be doing any significant walking today. As I have no interest in the challenge of doing 45 miles with lots of ascent in 2 days that means we won't be completing our Pyrenean route this year.
However, it does seem achievable (provided I'm back to full fitness tomorrow) to still achieve the completion of 'coast-to-coast across France'*. So, the question for anyone who would care to answer (and who has access to mapping on a screen bigger than 5") is what is the best looking direct route to the coast from Arles-sur-Tech? I acknowledge it'll likely be road walking all/almost all the way.
(*with a little bit of a detour to Spain every now and then)