The players should be free to rent whenever and how long. For example, the current season is on day 3 of 14. That means the season has 11 days left. If the player rent for 6 days, he would be renting the card from day 3 to day 9. Since this is on the current season, this cannot be cancelled by both sides. The player and owner cannot cancel the rental giving security for both of them.
If the player wanted to rent the card for more than the season left the owner can cancel the rent at the end of the season. For example, The current season is on day 7 of 14, which means the season has 7 days left. The player rented out the card for 30 days. Now, that card can be cancelled by the owner or player because it exceeded the days left for the current season BUT it would only be cancelled on day 8, which is after the current season. The card will still be rented by the player until the end of the current season, which in this example, for 7 more days. This compromise is so that the owners can adjust the price if needed to but will not give a bad experience to the one renting the card.
My suggestion is just combining the daily and season rental. This compromise doesn't force the players to rent for whole 14 days or the whole season. They can still rent 2, 3 or 5 or whatever but if the rent falls within the current season, it cannot be cancelled. That's the only difference.
If the player rents for the whole season, it still cannot be cancelled since it's still within the current season. In other words, it also acts as a season rental at the same time.
For the tourney issue, 
Lastly, for the unplayed accounts, I will be glad if you lend me one of those accounts if you don't play it. We can talk it more over on discord. I have discord link at the end of my posts here in hive. My discord name is 
RE: SPS Governance Proposal - Make Rentals Seasonal Only