There are several home exchange sites available where you might want to float your idea.
I did a home exchange with a couple from Istanbul for 3 months a couple years ago. Offer came out of the blue over Facebook (in response to a farewell post i made to a house sitting forum, when I realized that was not what I was after). Worked out like a charm for both of us.
I live in a penthouse in the Old Town of Cuenca, Ecuador, and would definitely be interested in such an exchange. Though I have a studio, it is not really set up for model shoots (more for product and the like), and it is actually one room I normally have locked up tight if doing a home exchange (our computers, cameras, etc are locked up in there).
We have been to Madrid, but only as a tourist stop of a few days. Would definitely be interested in staying there longer (as we did in Istanbul). Let me know if this would interest you (or others reading this, in other parts of the world -- we have visited 75 countries so far, returning from Namibia and Botswana just yesterday, with a month in India in February for Holi, and another trip planned for October to Vermont for Fall Colors).