Changing From Full Size Spare Wheel To A Space Saver

[macs]

I currently have a full size spare wheel in the boot of my Ford Focus Mk2 (07 plate) but I am going to need as much space in the boot as I can get for when my first child comes along so thought i'd get a space saver wheel so that the floor of the boot is lower.

Current set up is the full size wheel sitting proud of the base of the boot so has some polystyrene mouldings around the wheel and the carpet sits on those. The wheel is held in place by a long threaded rod.

Last night I thought i'd just see how much space there would be if I had a space saver so took the full size spare out and the polystyrene surrounds and put the carpet back in - it didn't fit properly.

It didn't fit properly against the different shape of the wheel well at the front, which is no big issue, but at the rear of the boot (i.e. against the back of the back seats) the hinge of the back seats protruded into the boot space and the carpet was way too small. I looked in my wife's Fiesta to see how her's is and it looks like her carpet has a padded flap at the back to stop the hinge showing - am i going to need a new carpet?

What parts do I need to get a space saver to fit properly? (at the moment I think i need a space saver wheel, a new carpet with board backing, shorter threaded rod, and possibly a new jack)

Will I need a new jack or can I just get rid of the polystyrene thats around it at the moment to drop it lower?