This is a bad idea. For the people who get to the later rounds there are possibly 5 fights, some people stall until the last second and then fight which means 50minutes of waiting and then additional time fighting, I've had 8 minute fights before so that's 90 minutes to finish spacetime. if you start at 21:00 and take 90 minutes then you don't finish until 22:30, most people have work to go to in the mornings so they wouldn't be able to stay up that late for a game, 22:00 is already bad enough for some people don't add another 30 minutes to that.

In addition, if you finish spacetime fast then you can still do last minute plunder, and you can avoid waiting until the last minute for convoy/ranked on your own, the difference for the ranked rewards isn't much and later on in the game you will stop caring, I have over 200k ranked coins that I have no use for.

the problem you have with 9tails is easily solved, kill 9t faster, my server doesn't have that issue we can finish 9t by 20:32 at the latest and since it scales you can manipulate its health so you finish at the right time.

the needing to refresh thing can be done in advance, I normally refresh after/during decisive bonds to make sure I won't see bugs like that during 9t and spacetime.