i have been searching the internet lately for these as well. not too many options. i really like the rasta setup the most. my spare is full size and too small to fit under the truck, so i have it bungeed down against the driver side panel in the rear cargo area and built a little "table" to fit snugly against it that is the height of back seat to cover up all my junk in the rear cargo area.
I carry 2 spares. One under and one in the cargo area when I go to more remote areas.
You can fit the full size under the car. I have BF goodrich 265/65/18 that are 31.7" new and I only had to deflate to about 25 pounds to get it up which is more then enough pressure to get me down the road to fill it up more if I don't have my compressor on board. Removing the plastic mask will give you more room.