He did say loss of trunk space is not a concern.

I think it's a bit silly to do IMO. 1st you are now carrying more weight than you normally do. 2) You lost trunk space. 3) Tires wear by age as well as by milage, so you could end up with a tire that is fine but old. 4) Chances of you ever needing a spare are small. If you do use it, it's only temporary until you replace or fix affected tire. In either case, you will need to fix affected tire ASAP.