Randomly stumbled upon your comment and going to share my 2 cents. As you maybe remember I don't really play the game so what I suggest can be totally wrong 😄

I really like your suggestions and to make those even better I would add a 3rd one:

3. After implementing point 2 we should change how rentals are priced. Instead of a daily price we should just have a "season" price. If you can only rent for one season there is no point in having a "daily" price.
This will also greatly help with your 1st point as the "whole DEC" increment is going to be easier to accept if applied to the season price.

3a. Expanding on this even further you can decide that the minimum season price is actually 5 DEC. Still up compared to what we have now, but not so drastic as 1 DEC/day.