When in Portugal, I only drive hire cars so post 31/12/20, as a tourist, I will drive on my UK driving license, endorsed with an international permit and carry my passport.No idea when we are likely to get to the Canaries... we are engineless, broke and waiting to see what develops.
Still no idea whether it will definitely be 90/180 from next year, but may leave the boat in Bruce's for a while anyway.
Re. Portuguese residency - another can of worms seems to be driving licenses. If I get residency then I need to swap my UK license for a Portuguese one before the end of the year. I guess the solution to this is to forget ever driving in Portugal, as I am more likely to need to drive while in the UK.
From experience, unless you appear to be breaking the law, hire cars appear to get little attention from the constabulary.
On the financial front, given the limited amount of driving we do, hire cars are a cheaper option than having a car in Portugal and far less hassle.