Derek,
I think that Copper-grease can be applied to treads without any risk of them loosening. But, as for all things, apply with moderation
And no, the space saver is an option here. We have the tire-fit-kit and no space-saver. And as a plus loads of extra space under the floor.
Our country is very small so we really don't need a space saver, the mainpart of our country is one big metropole with infrastructure everywhere.
I would like the tire though, it would give me a safe feeling on a skiing vacation but the dealer charged some 300.- Euro's for it.