When finished I'll just carry a couple of cans.
Even if yu had a space saver made up etc, you've still gotta carry your flat somehow - don't think your passenger you be too happy having your rear wheel on his/her lap for the ride home!
Also some cobras probably don't have a choice about carrying a spare. Eg CR's have Jag front with a Ford AU rear so you've got a 50% chance of being able to use it. (I bet Aussie Mike has a solution to this problem though
)
Cheers