I have been thinking of trying something similar, but will need to use some self-control, since a lot of the cards I might be renting I have spares laying around (some are even on rental market, and it will be awkward to rent from myself, lol) so while emulating how this might go I foresee a path where my rental test becomes heavily entangled with my collection, one card at a time.
This gives me hope that I might be able to do it without getting carried away.
I appreciate the level of detail provided here - great post.