mwest

I've searched around here and found only one thread almost 10 years old posted by a Lotus guy for a rack system using suction cups to carry tires. But, evidently he's no longer in business.
I'm looking for a simple system that can carry at least 1 tire on the roof and can be installed and removed in minutes and does not need a rack or rails to be installed.
I use my Cayman for track days and do carry a donut spare in the rear trunk. Ideally I'd like to carry at least 1 full size track tire on the roof.
Years ago I made a simple rack using 2 by 4"s and suction cups and cam-lock straps to carry 2 kayaks on the roof of my Mazda Protoge. It worked and surprisingly did not damage or scratch the roof. It's not a contraption I'd trust on the Cayman.
Searching on line I've found a few options that are essentially canvas bags designed to be installed with or without roof rails. They are padded on the bottom to protect the roof from being scratched.
Has anyone used any of these systems or come up with some other simple way to carry at least 1 tire on the roof.
Thanks