This hanger is suspended from the trunk floor with four bolts and large washers to spread out the weight. It is five inches tall. Those are wheel studs sticking down so the spare tire uses the same size lug nuts as the car, so only the lug wrench is needed to dismount the spare. That 1.5" square aluminum tube bolted in forward is a spacer so that the tire is resting equally on it, the middle trunk stiffener, and the bottom of the back of the trunk.
Here you can see the bolt pattern in the trunk. One result is that the spare hangs about an inch aft from the UBUYGAS installation.
I cut the plastic air diffuser similar to UBUYGAS though at slightly different places because I also had installed a bike rack that required some close fitting. I used Lynch pins to hold it up, and for good measure added an aluminum stiffener. I used 3/16" aluminum rivets for the hinge and stiffener connections.
And there it is. Considering how much time it took to work all that out and fabricate the parts, it doesn't look like all that much in the end. I stole the jack and tools from my old decrepit Toyota. So now I have self rescue available in case the compressor and a plug kit are not enough.