Mid-term rentals Portugal/Madeira?

Hi.

I’m a UK citizen trying to establish residency in mainland Portugal before the end of the EU transition period. I will need to travel back to the UK periodically owing to the ill-health of an elderly relative.

I was therefore intending to move initially to Madeira (from where I can return without a two week quarantine period) until the virus situation settles (assuming it does). I am advised, though, that the minimum term for property rentals in Portugal is now one year, which is longer than I had envisaged being in Madeira.

Does anyone know if shorter lets might be available and whether they’d be acceptable for residency purposes?