Simples, kick the Porker out of bed and slip the Maser in!
If really not an option, I had a Permabag a few years ago and they are very good. They do an outdoor version now and by its nature will not flap about. If it goes in clean and polished, it will come out the same, be it 1 week or 6 months.
I have considered kicking the Porker out, however although the Mas goes in the garage, it is quite tight where as the Porsche fits in nicely with plenty of room, and then the Porsche (which is the slightly higher value car) gives me the same problem.
After much deliberation and talking to my detailer, he recommends leaving the car out to endure the rain, wind and airbourne contaminants which are likely to do less damange than a car cover. His exeption to this was if it was under a tree with sap / bird dirt issues (which I do not have) then the car cover would be the lesser evil.
This is particularly the case as the car as a GTech protection
So regular cleaning and driving is the order of the day (and a future house move to a double garage)!
Thanks for all of your inputs