That can of slime, urrrgh.
I prefer a real wheel. Even a space saver (wheel barrow) tyre is better. My BMW came with no spare - the original owner ordered it without.
I've since bought a used spare, same alloy and tyre size as the rest. With my S8, I've never used the factory Widow Maker, 1,858 kilos being lifted by that thing gives me the shivers. I purchased a hydraulic bottle jack, a lot safer, small enough to fit in the spare wheel recess and it doesn't tilt in use.