Car insurance agencies only insure your car if you lend it to someone but if you rent it to someone they don’t insure it. Can you rent your car to someone on condition that if something happens he should be a shoel and not have to pay rent, and then collect insurance and say you only lent it?
To my understanding, this condition would not avail. The insurance company insures the car on condition that you don’t rent it out. If you make a rental contract you lose the insurance, even though the clause will turn the rental into a loan should something go wrong. It remains a rental contract, and would forfeit the cover.
In general, the approach I take in halachah is to avoid ‘yeshivishe shticks’ (if you know what I mean). As I have heard on numerous occasions from Rav Asher Weiss, taking such ideas out of the beis midrash and into the world of commerce can become a dangerously slippery slope.